I found a reference for ALS.

"The Advanced Launch System (ALS), was a US Air Force funded effort in 1987-1989 to develop a flexible, modular, heavy-lift, high rate space launch vehicle that could deliver payloads to earth orbit at a tenth the cost of existing boosters.
...
Seven contractors were awarded five million dollar, one year study contracts in July 1987, with the studies to recommend a family of modular boosters with low earth orbit payloads from 2,400 kg to 90,000 kg. The new launch vehicle was expected to make its first flight in 1998, reach full operational capability of up to 30 flights per year in 2000, and replace all existing expendable launch vehicles by 2005
...
Total development cost of ALS was estimated as $15 billion through its first flight in 1998, and the low launch rates expected in the absence of a massive Star Wars deployment could not pay back this investment, even with a substantial reduction in costs per launch. By 1990 the program was reduced to a $150 million per year propulsion development effort. However the technologies identified for use in ALS would be found in 1990’s upgrades to the space shuttle, the USAF Evolved Expendable Launch Vehicle program, and numerous commercial booster programs and proposals. "
http://www.astronautix.com/lvs/als.htm

So, the EELV was somewhat a result of this ALS idea.

Delta IV Heavy:
Launches: 2. First Launch Date: 2004-12-21. Last Launch Date: 2007-11-11. LEO Payload: 25,800 kg (56,800 lb). to: 185 km Orbit. at: 28.50 degrees. Payload: 10,843 kg (23,904 lb). to a: Geosynchronous transfer, 27deg inclination trajectory.
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Delta IV Heavy Upgrade 30 t. Status: Study 2004.
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Delta IV Heavy Upgrade 35 t. Status: Study 2004.
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Delta IV Heavy Upgrade 40 t. Status: Study 2004.
...
Etc
And:
Delta IV Heavy Upgrade 94 t. Status: Study 2004.

Proposed upgrade to Delta IV Heavy by clustering seven common booster modules, using a new RS-800K engine in the booster stages, an AUS-60 upper stage powered by 4 MB-60 or RL-60 27 tonne thrust Lox/LH2 engines, and aluminium-lithium lightweight alloy in place of the existing aluminium in all stages. Payload fairings over 6.5 m diameter could be accomodated. Introduction would require new launch pads and booster assembly infrastructure.
...
Next Genertion Delta 100 t. Status: Study 2004.

Conceptual next generation Delta booster beyond Delta IV Heavy, equalling Saturn V of the 1960's in payload capability. The booster would use two parallel 7-m-diameter booster stages, a notional RS-XXX Lox/LH2 rocket motor, and a 7 m diameter upper stage and fairing. Payload fairings of 7 m diameter could be accomodated. Introduction would require new launch pads and booster assembly infrastructure, and a new factory to handle the larger-diameter tooling.
http://www.astronautix.com/lvs/deltaiv.htm

And as far as Altas V:
"Status: Design 2003
Heavy-lift version of the Atlas V launch vehicle system with three parallel 3.8-m-diameter Common Core Boosters (CCB), and a stretched version of the Centaur upper stage (CIII), which could be configured as a single-engine Centaur (SEC) or a dual engine Centaur (DEC), and a 5 m diameter payload fairing. As of 2004 no work had been authorised to build Atlas V Heavy facilities at either Cape Canaveral or Vandenberg AFB. "

And other heavy variant which in design stage:
"Atlas V Growth Phase 3. Status: Design 2003.

Proposed Saturn-V class variant of the heavy-lift version of the Atlas V launch vehicle with five parallel 5-m-diameter wide-body Common Core Boosters (CCB), each with 1 or 2 RD-180 engines; a 7-m-diameter new Lox/LH2 stage; and a 7 m diameter payload fairing.

Payload: 44,000 kg (97,000 lb). to a: earth escape trajectory. Liftoff Thrust: 35,300.000 kN (7,935,700 lbf). Total Mass: 2,900,000 kg (6,300,000 lb). Core Diameter: 5.00 m (16.40 ft). Total Length: 63.00 m (206.00 ft). Span: 15.00 m (49.00 ft). "
http://www.astronautix.com/lvs/atlasv.htm

As for your particular points.

Google: the speed of light = 299 792 458 m / s

Or 299,792 kilometers per second

And a 1/10th speed of light would be 29,792 km/sec.
At a constant velocity of 29,792 km/sec one would reach 4.2 ly distance in 42 years.
And at constant 1% of light speed it takes 420 years {2,979 km/sec}.

"1 light year is 63,270 AU
...
If you include all the comets like we did in the second part, then the Solar System has a diameter of about 100,000 AU, which means it would fit 2.7 times between the Sun and the nearest star. "
http://curious.astro.cornell.edu/question.php?number=374

"Pioneer 10 was launched March 2, 1972" and as of "December 30, 2005 Pioneer 10 was 89.7 AU away from the Sun"
http://en.wikipedia.org/wiki/Pioneer_10
So, Pioneer 10 is around 1/500th of distance thru our "greater" solar system [including Oort cloud]

Now, if you send a probe to Centauri at what distance from star do you start study the star system using this probe?

Suppose you wanted to begin at the moment you entered it's solar system [about 1 lightyear from the nearest star of the 3 star solar system] that means one doesn't need to travel 4.2 ly but 3.2 ly years to use the probe to study this star system. And suppose as result studying this star system you found planets you wanted to get closer to to study them better?
Or suppose you wanted to study the Centauri star system before the probe actually entered it- around 1/2 ly before this- or about 100,000 AU from the nearest star, but a possible 100 to 1000 AU from some planetary or Oort cloud type object.
So, roughly it has the capability of detecting and studying a Pluto at say 500 AU. We study Pluto at 30 to 50 AU from Earth's surface, presently. E.g:
"Using the Submillimeter Array, or SMA, a network of radio telescopes located in Hawaii, astronomers found that Pluto's average surface temperature was about 43 K (-382 degrees F) instead of the expected 53 K (-364 degrees F), which is what the temperature of Pluto's largest moon, Charon, is. "
http://www.space.com/scienceastronomy/060103_pluto_cold.html

Now, if this probe can study the Centauri star system from a distance of one lightyear or more from the star, then it could also study the Sol system on the way out to up a distance of lightyear or more from the Sun.
Leaving about 2 ly of transit distance between the solar systems. Now if the average velocity for these 2 lys is say 2% the speed of light, then this transit would take 100 years.
So, from launch date to end of study of Sol it might around 80 years, then 100 years transit, follow with 80 or so years of studying Centauri star system- and to study the Centauri system for 100 years [and you wouldn't need to decelerate].
To breakdown further, you could spend 20-30 years, building, testing, and traveling thru Sol system at relatively slow velocity [using gravity assist and not requiring exotic propulsion systems]. Using probe as radio relay/internet hub and part of Earth or other radio telescope network. Etc. You could also use it platform to test interstellar drives or as "reason" to develop interstellar drives. And the remaining 50-60 years it would travelling at a much higher velocity towards the Centauri star system while study the Sol system.