I agree the amount of people playing it like CoD and dolphining is out of hand, luckily it's not full on like CoD and most people who try it die spectacularly, but I would like to see mobility toned down a tiny bit. Disagree on shotguns though, I think they're in a great spot: close quarters is where they're supposed to shine. If anything maybe their range can be clipped a bit because ~20m seems a bit excessive, but they're a difficult to balance gun and if you take away one shots they quickly become useless and we're back to CoD's "Everyone uses a SMG" game.
Vehicles don't all move at the same speed, only the IFV and MBT are really ponderous, and even then only if they have to maneuver in tight spaces. They could probably use a bit more deflection on frontal armor since as it stands two engineers w/RPGs can out DPS a repair and good positioning, but only a bit. As it stands, you really should be thinking about how much of your tank's body is showing at any given time and keeping a low profile, as real tankers always have to keep in mind.