+1 on Laitch's advice above. I doubt that your air filter is in need of replacement with under 10,000 miles on the bike. Since they are pretty expensive, and usually good for over 50,000 miles I would check it but put my money into fuel lines and a fuel filter(NAPA Gold 3240 is the number, I think). You don't need the stupid expensive BMW filter, almost any metal shell filter with 5/16" inlet/outlets will work. NAPA gold is their premium line for fleet operators.
I don't think you need to pull the fuel level sender, just drain the old fuel out and do a vinegar soak. The sender has some fragile wires and I wouldn't want to take a chance on handling it.
Judging from the inside of the tank, I would plan on doing a soak with Techron in the fuel injectors before I got serious about using the bike. Same with the fuel pump. Once the fuel system is cleaned up and all the parts functioning you can move on to balancing throttle bodies.
While the tank is soaking is a good time to tackle the rest of the fluids: forks, trans, final drive, forks, cooling and brakes.