You can use group tracks or FX-channels for effects. A good tips is to use the group tracks, they have more funcitonality than the FX-tracks. You can also print the effects right away on your tracks by right clicking and choose a plug/effect from the meny. If you have a "recent" edition of Nuendo (2, 3), you can "freeze" the tracks. It frees all the cpu power used on the plugs on the track, but you loose some functionality (you can still adjust volume and pan). You can "unfreeze" the track(s) whenever you want (it takes approx 10 sec depending on how powerful your PC are). You can only export one track at a time, unless you use a third party plug called "TapeIt". Someone over at the cubase-forum has made a macro to export multiple tracks, I think it`s called "unattended export tool" or something like that.