Do not change the display mode unless you know that that mode is supported. Use love.graphics.checkMode to check whether a mode is supported or not.

Also note that calling this function will cause the entire display context to reload. This means that all Images, Fonts and other graphical objects will have to be reloaded. It is therefore advisable to call this function when as few objects as possible has been loaded.

FSAA stands for Full Scene Anti-Aliasing, and it is recommended to set this number to 0 (the default), unless you need anti-aliasing of the edges on primitves and images. Most machines who support this feature support 1, 2 and 4 FSAA buffers. The more buffers, the better the anti-aliasing and the slower the performance. Assuming you're not using filled primites, you do not really need FSAA as long as you pad the sprites with some empty space; in this case FSAA will have no effect on the visuals at all, it will only hinder performance.