Hi Ken, comment ça va!

Asteroid detection:
Why not ESL1 and ESL2 ? Finally, a satellite aimed at things around our planet, with a stargraph hiding the Earth for the glare!
And another camera could be aimed a the Full Earth... And here comes Triana :-))))

The Moon:
Well, the Delta V is higher than for Mars, but only on the way to Mars. If we want to get back from the Moon, it's going to take a lot less energy than getting back from Mars!
I imagine a trip to Moon orbit and from there, land with an open vehicle, where astronauts are all the time outside in the vacuum of space and landing next to a pressurized wheeled vehicle (because they'll be explorers, they'll need to move). Because the lander would be open to vacuum, it would be very lightweight. Even more, to return back to Moon orbit.
It's powered descent and ascent, true, but generally, if an engin fails, it happens at the moment of ignition which means the crew can still be salvaged while in orbit.

Mars:
It's so far away, it exposes anything to much more solar radiation and cosmic rays than if the destination were the Moon.
Some of the Russian failures are attributed to long exposure to those radiations combined with less effective solar panels.

I doubt very much humans would accept landing on Mars with airbags (especially if they've seen "Red planet")!
So, they'll land with a heat shield, parachutes and rockets! They better work (those rockets) and keep the crew steady and able them to chose precisely the landing site (much more difficult with parachutes).

I wonder about returning back to Earth with a vehicle that is not the same as the one that took astronauts to Mars. If there's an undetected failure and they can't return back....But if they check the Mars lander, before landing, while still in space and detect a failure then they can abort landing....

Search for life: Viking tought us that we really are not sure what life is; we don't have a good definition of what it is.
It's not a good idea to reproduce on Mars conditions that only exist on the Earth to see if there's life on Mars.

ALH84001 (the meteorite) tought us we don't even know all the life forms on our own planet: the worm shape was so small it couldn't have been from Earth. But later on, apparently, scientist did find similar earth lifeforms!

Plenty to think about.

Raoul