Where is the console?

Ctrl + Alt + ~ will activate the console.

Once there, if you wish, "seta com_allowconsole 1" will enable the normal method of opening the console via the tilde.
The seta specifies that it should be saved into your config.

My FPS appears to be capped at 30, how can I fix this?

Quick answer: ensure com_unlockfps is set to 1, and com_unlock_maxfps is set to 60 or higher.

Fearog of SD has written up a post about the relevant commands that can be read here.

The game crashed and now my gamma is broken, WTF is up with that?

An annoying side effect of most id engines.
This can be fixed by relaunching the game with this commandline: +set r_brightness 1 +set r_gamma 1 +crash
which will load up ET:QW, set the gamma, and then, well, crash.

Are there any additional tweaks for FPS?

Drop down your console (CTRL + ALT + ~) and type in this command:

setMachineSpec 0

Example: (which will lower the game to minimum graphics (which still looks pretty damned good, might I add!) YMMV, but I can go from 15->35FPS, hitting 60FPS indoors on a 1.8GHz e4300, and a cheapo ATI X800 GTO)

For "setMachineSpec 0", which will set the graphics to low, and exec a config which contains some commands suitable for low end PCs.

Additionally, r_shadows 0 will provide a significant boost indoors. Due to the nature of the ET:QW engine, this will provide a minimal boost to shadows being cast by the sun.

I have a (really expensive NV card), but I only get (really low) FPS, what's the deal?

NVidia drivers appear to have a problem with Multi Display Performance Mode. This can be resolved by setting it to Single Display Performance Mode.

Go into your NVidia Control Panel, under 3D Options, and set "Multi Display Performance Mode" to "Single Display Performance Mode