You're not a pain, just need to lay out the questions so us pedants and old duffers can follow you!
Anyway - sticking with Military 1st for a bit the Helikon BDUs are great trousers and are "proper" BDU style in as much as they are fairly loose cut with a plethora of storage options. They don't have pockets in the knee for pads of any sort though (but they are double thickness reinforced).
Helikon SFU trousers are a more modern cut so they fit a bit closer but they also have built in pockets for knee pads (which you would need to buy separately).
If you want something a bit more tacticool then you'll want to look at some of the Crye G2/G3 type trousers that have those little plastic kneepads in them (they're actaully attached to a much larger foam/neoprene type of pad internally), I'd suggest looking for brands like Emerson if you want to stick inside your budget (try www.shootercbgear.com although dispatch will be delayed because of the Chinese New Year - you can get them in the UK/EU but they'll cost more).