I forgot to add 1 thing to my list!
Some kind of spawn protection from grenades and Helicopters. For example,you spawn and a guy has tossed a grenade right at your feet at the same time. You should have 3-5 second immunity to grenades after spawning. Obviously you can't make spawners immune to everything, or else the "Spawn Camp" (everyone sitting in their spawn and waiting on people to come get them) would be even more prevalent than it already is. Seems like every other game the opposite team holes up in their spawn and camps like the giant dickholes they are.
In fact... I think every corner in the game should have a platformer-esque Spike strip that juts out and murders anyone camping there every 3-5 seconds. Death to campers!