Been playing Cod4?

For headicons, you could make 45 xmodels which are just flat textures that turn to face you, and link them to the players, eliminating the need to use any normal headicons.

You can probably make several different menus for the different ranks, so if their rank is < 10, give them the bolt-action menu, etc. If you don't want low rankers to pick up high ranking weapons then you could make a system that drops them too.

Health packs are possible; look in AWE's scripting for them. You'll just have to change the hud a little and make it so they don't apply over time.

Artillery strikes could be several different weapons all with the binoculars model, with different amounts of damage and stuff, you can also change the time it takes to fire in the weapon file.

There may be one or two knife mods out there, but most are packaged in with other mods - you might be better off using theirs, with permission.

Also, welcome to Modsonline

One small thing, how do you plan on keeping track of which level someone has?

I think Caretaker was asking how you were planning to track a player's rank, not how you were going to symbolize it? It sounds like a player would have to start all over each time that he joined the server with the bolt-action rifle only rank. Or do you have something in the works on how to track what rank the player was the last time he was on the server, so each time that he is playing he can build onto his previous rank? And I wonder if the player would lose his rank each time a map started?