What I'm talking about is research. Do you: Spend money on research as soon as possible even if it leaves your team struggling to get vehicles? or Conserve money in order to afford more vehicles with specific research.? The first option sounds completely stupid when you compare both of them, but in game, it's either they get vehicles or have their life wasted against an enemy tank, so I almost never restrict vehicle creation even if we're on constant under 1k res limit. The 2nd method seems smart planned, but it gives the enemy more time in order to advance, so if you don't manage to hold back, it'll be a struggle to gain back lost land.
Vehicles in the beginning can give you a big advantage, but too many are not really useful, as you couldn't hope to take down a lot of buildings ANYHOW (STD Cannon doesn't damage them a lot). They are only useful for fighting other vehicles and pressuring your opponent. Later in the game advanced technologies are crucial to your success. So I'd say... Conserve, but not too much and in ANY CASE be sure to give everyone who knows what he's doing a vehicle, cause even with jeeps they can turn the entire game around.
You can take down a building with some effort with 2 LTs/AFVs spamming Cannons and MLs with bio diesel, and easily with 3 light armors, even with engineer or 2 repairing it.
Depends on how much map control you have and the map. Some maps you aren't going to get anywhere with paper tanks/apcs like on crossroads so you might as well restrict meanwhile on duststorm a paper APC rush early on to the enemies main can be devastating and more than worth putting off research for a couple of minutes.
i tend to restrict vehicle creation and allow only single apcs to be built. i dont really care about the drivers, everyone needs training and thats why they play on public servers. somewhere between 1.5-2k res and low income (less than half the res sources on the map) is the limit were i start to think about restricting, that doesnt mean im doing it btw. thats something depending on players too. if you have good players, or at least reasoned players, you just can ask to keep vehicle usage low until you get something better (noone likes paper anyway) but on the other had, if your team consists mainly of n00bs and they use (waste) their tanks like they were heavies with composite ... i restrict. in general i keep an eye on resource income, tax how long it takes till we can afford another vehicle and decide if we need better research or more tanks. its also a good plan to stop researching for a bit once you have your first tank-layout done to actually give your team the chance to build that tanks, especially on maps with little income. also if you dont manage to get your forward rax up, even a paper apc can safe your asses (nadeboat with crew > rax)
I never get a VF unless either we have a ton of res or we have some research going. If i cannot keep research going continuously up until engines/armor/weapon, then i'll restrict until I have enough money. There is no reason to restrict vehicle creation if you have over 1.5k res on average, save the 3 minutes it takes to research heavies or something. Restricting is also a good way to get a few people into the VF ready to roll off heavies the moment they are researched. Overall, it greatly depends upon your team. If a tank drives out of the VF and less than 300 res drops from your reserves, it's time to restrict until people stop buying shit tanks with no armor.
If the team (infantry, mainly) is half decent, they'll be able to at least hold the frontlines against a couple apcs/tanks and other infantry. I tend not to allow vehicles into the fray unless we're doing badly, in which case i'll slow on the research to provide a little more stability to our resources. Otherwise, i'll invest in plenty of research before i make vehicles available - to reduce the number of weaker vehicles on the field. (face it, plain armour is totally worthless.)
RPG + mines > standard anything. Mortar + RPG + Mines > most armor on any light vehicles. A standard rush is just asking to be killed. first, if there are any ML's, the rockets from grenadiers become one hit kills. Second, anything less than 3 standard engine vehicles will overheat before you can kill the com.
If I rush a specific tech that I'm confident will have an edge (like BioMG vs enemy regen armor) I'll stop researching and spam vehicles. Otherwise, you're just setting yourself up to fall behind in tech.