Well first off welcome to defence talk.
If you want to have a conversation on hypothetical vehicles we do have a various subofurms where it is appropriate to do so. When asking about aircraft, use the Air Force subforum, when it's ground troops use the Army and Security forces forum. A word of caution, this website is populated by many people who have served in the military or work in the defense industry, and as such have intimate knowledge of weapon systems, and why they are designed the way they are, so I would highly encourage you to read the rules, and do some background reading before asking question such as these.
In terms of incapacitation, that is partly why we switched from the 7.62 round to the 5.56 (or 5.45 for WarPac). In terms of programmable ammunition, this is being researched. A bullet is presently too small, but it's being done for grenades (fired from grenade launcher, not hand thrown). War of the Worlds is a very bad example to use. Those machines would be in real life extremely vulnerable to light infantry with modern RPGs or ATGMs hiding in the brush and taking their legs out.
