Pickup kits would not solve unknown cache spawning necessarily, but it would definitely slow it down, especially if a hybrid approach were adopted. If the only kits available for request at an unknown cache were Cell Leader, Warrior, and Civilian, there is much less incentive. RPG kits especially, and PKM and RPK kits are the biggest draws to spawn on unknown caches. As a possible alternative, would it be possible to have those three kits not spawn on cache locations until they change to known caches? This way, Insurgent teams would still have that firepower at known caches, but the incentive to spawn on unknowns would be reduced greatly.
I love your flag/counterobjective idea. I think that the most obvious incarnation of this idea would be to add Vehicle Checkpoints to insurgency maps that do not have them. Most maps have a VCP, so this should not be overly difficult, however, as I am not a mapmaker, I may be speaking out of turn on that.

Start the point under Blufor control, give them an option to spawn there for a limited time at the beginning of the round, (and as an adjustment start both weapons caches unknown) and give Blufor a steady flow of intel points as long as they hold it, at a rate to be determined. This would be to simulate the steady flow of intelligence from Blufor stopping and questioning civilians in the combat zone. Yes I know they are not really there, but this is Project Reality, and I do try to ground my ideas in some semblance of reality. I do not know the current values needed to expose cache locations, but I would recommend a rate that would expose one cache per hour, so that if Blufor decides to just camp in VCP, they can not get enough intel to locate all caches within the round time limit. They would be required to at least patrol and engage to some extent. However, if Blufor is actively fighting and engaging, not to mention actively defending against the Insurgents rushing VCP, this should result in a fairly smooth and consistent flow of gameplay. Obviously, testing and tweaks would be in order.
If the Insurgent team is able to take the VCP from Blufor, I suggest a one time intel point penalty (rather than a bleed of tickets or intel) each time the Insurgents take full control, rather than at loss of control, to simulate loss of the intelligence material that would have been inside the checkpoint when it was overrun. Additionally, for the duration that the VCP area is held by the Insurgent team, I suggest that the Insurgent team have access to some spawnable pickup kits inside VCP. One one hand, I kind of like the idea of there being a couple of Blufor kits being in there, simulating taking the arms room, but on the other hand, I don't want to unbalance a map. I am thinking probably one additional arty IED kit, simulating rewiring the munitions left behind, and perhaps some Blufor optics rifleman kits, no more than two or three. Maybe throw in a single Blufor Rifleman AT kit, but I am undecided on that. It would depend on the map, Blufor assets/layer, and overall balance. Again, I do not want to unbalance a map, and that is an extremely powerful kit to put at the Insurgent team's disposal. Yes I know they can get one if a Blufor soldier loses it in the field, but that is a different ballgame than having it spawn under the Insurgents' control.
I think this would definitely up the fun factor all the way around. The Insurgents would have something to "base rape" while keeping main as a safe haven as it is on most reputable servers. Those that like that kind of game play could throw themselves at VCP mercilessly, as well as the Blufor guys getting to play starship troopers on the Insurgents zerging the walls. Additionally, it would give an option to break up stagnant gameplay on maps that take forever, or stall on caches that are well defended or in bad locations. Ticket loss for Blufor defending VCP's would be an issue, as Insurgent teams would theoretically be able to just bleed Blufor dry by hammering the VCP, so perhaps a ticket increase on the Blufor side would be in order as well.
On a separate note, can you guys take a look at caches in destructible buildings? Often the buildings are destroyed and the caches are buried in the rubble and rendered invincible or invisible. Also, on the map Karbala There are frequently two caches that spawn in the southern section of the map. The cache that spawns in the western most section of that village, just east of the river, sometimes spawns inside a building. Not inside a room, but physically inside a building, to the point that it is completely invulnerable, and can not be located to be destroyed, short of perhaps carpet bombing with C4, which would be a lot of fun to watch, but ultimately, is not very practical. This is not a common bug, but I have seen it happen more than once.
Additionally, I think there is a separate thread running discussing civilians, and their role in the insurgency game mode. Do we want to bring that discussion here since we are tackling the game mode as a whole? That system needs a lot of love too.
To revisit the ammo techie issue, I can see the original intent, but I don't think that the execution has the round playing out quite with that same feel. Maybe have a second ammo techie spawn in at the 20 minute mark and increase spawn time to ten minutes or something along those lines if the dev's aren't willing to let the poor backwards Insurgents learn how to throw a box in the back of a technical.

Those trucks are the lifeblood of the Insurgent team. Blufor can drop an ammo crate with hummv's, and supply crates with logi trucks. Insurgents don't get supply crates at all, and to have half of their mobile supply source unspawnable is rough.
I thought of one more thing that is desperately needed on the insurgent side. The Insurgent team obviously has demolitions work down to a science. Can the dev's pretty please with pink sugar on top give the arty ied kit a wrench? We need some way of removing mines placed by inexperienced sappers or blatant asshats that do things like mining exits to insurgent main, or put mines under key assets like Gary's inside main bases. As it stands, our only option is to lose the asset and wait 20 minutes for the respawn, or in the case of a mined exit, sacrifice a vehicle to clear it. With the Insurgent team's obvious demolitions expertise, it shouldn't be too much of a reality stretch to implement this.
All in all, I am loving the fact that Insurgency is getting some love, or at least some attention. Keep up the good work.