having triggered IEDs partially underground is reasonable imo, though PR has always shied away from having powerful self-exploding munitions, so I'm actually happy to keep the mines above ground, however it might be a good idea to change their colour to something less green for desert/afghan maps, so its not quite so easy to see.
The choice gameplay wise imo is this
1) Readily avaliable placeable explosives that aren't hugely powerful (e.g. we have spawnable IED insurgents)
2) Limited placeable explosives that are pretty damned powerful (e.g. the talib maps generally rely on requestable combat engineers)
having combat engineers requestable only from main would go hand in hand with any buffing up of their capabilities imo, as in the insurgency gamemode they would be pretty awesome with more power; so their avaliablity would balance that.
Blufor being able to destroy the enemy IEDs would be imo a great addition, however if I understand it right, its a compliated material thing, that I have no idea to do; so I assume its in teh queue like so many things. as far as a detector goes, I don't think it would work right ingame and the death rate amongst combat engineers ingame would be so high it wouldn't be funny, since usually on talib maps the IED you are about to poke is going to explode.
Pressure plates would be interesting, but I don't think you'd be able to simulate them properly ingame, a detector with a shaped charge near it would be awesome, but I think its beyond BF2.
Huh? Civilians and insurgents hit IEDs and Mines all the time... They dont magically know where it is... Quite comical though.
It is true however, according to books like 'Ordinary soldier' the Taliban do maintain a reasonable amount of chit chat with locals about where IEDs are, lucky for us since some of that intel reaches us.