I used to recommend ZebGames to everyone, but they went belly-up without telling anyone. That was fun. Ever since that happened, I've been using GameServers. I've only had one problem in the 4 months I've been using them, a lag issue at the beginning, and they moved the server to a new box with no hassle.

Advice for plugins: Step 1 is to get your server running first. Installing mods on a server that isn't running perfectly will make you never find the solution the inevitable problem. This is a good example of what your server.cfg file should be, but save a copy of the default server.cfg that your hosting provider gave you. If you're having a problem with rate settings, use their numbers.

Actual mods: The newest versions of Metamod and Sourcemod. Sourcemod allows for customizable map votes, easy administrating (/ban in chat instead of rconning into a server and finding a Steam ID, etc.), and tons of plugins. (Oh, and Metamod is a requirement for Sourcemod.)

Traffic: If you're planning on a vanilla server (normal spawn times, crits on, damage spread on, everything default like that), playing only Valve maps (no custom maps), you should register your server with Valve. That allows your server to show up via the "Play Now" button. If you're planning on nocrits or fucking with respawn time, the only way you're going to draw people in is to get a good community of people. So spam /r/tf2. :-)

Maps: It's your server. Until you have server regulars, it's all up to you, but if you want to play the popular maps, here's a list of what I've seen:
CP: Dustbowl, Foundry, Gorge, Gravel Pit, Steel
CTF: 2fort, Turbine
KOTH: Every map except Lakeside and the event maps
PL: Badwater, Gold Rush, Thunder Mountain, Upward
PLR: Hightower