"See a guy planting a bomb or shooting at soldiers, either shoot him or arrest him - he's a terrorist."

You very rarely see anyone planting a bomb or shooting at soldiers.
At most you see someone who is holding something that looks like a gun which appears to be pointed somewhere and you might even hear sounds like this gun is being fired. But if the person who is doing this watching is in a war zone and this person is a soldier, you are not playing man to man coverage, you are playing zones, and you don't wait until someone is actually in the act of shooting another soldier [if you are spending any time watching instead of shooting, that guy is either killing your buddy or killing you].

"Get a tip from a "reliable source" that the Ali brothers in apartment 2b were responsible for planting the IEDs you found - according to you they're fair game for ritual murder, torture or indefinite imprisonment.
According to me they're entitled to due process."

According to me they aren't entitled due process. Not the due process of an America citizen {or a Brit citizen} not in a combat zone or area of unrest. Instead what you want is effective measures which will hinder planting bombs or shooting at citizens or soldiers. For example, if you have a reliable source, you might temporily detain that source, and bust into apartmart 2b, and the soldiers will do whatever is needed to ensure as much as possible that they aren't endangered, next in importance, they want anyone in Apartment 2b alive, because you want to detain and question them. And "I will only talk to my lawyer"; or press charges or release me isn't part of the procedure.

See a friggin difference yet?

"Ritual murder" isn't effective, nor legal for any of Coalition forces in Iraq or under any circumstance. Nor is torture. And our soldier are honorable people defending the security of our nation- to suggest that our soldiers in general are doing this without offering specific evidence [as though it's self evident] is an unworthy act for good citizens to do.

Indefinite imprisonment is part of any war. Enemy soldiers have certain established rights and with any rights, there is also responsibilies which define what a soldier is. Illegal combatants are persons behaving similar roles as soldiers but have violated what is defined as a legal combatants [they have commited war crimes].
Soldiers and illegal combatent may have indefinite imprisonment- for soldiers it's generally until the war is over and/or there is a prisoner exchange. Illegal combatants is a subset of legal combatants and can be tried by miltary court and punished- unlike POW.