I/O Buffer size

No, the buffer size has no bearing on the quality of the bounce - of an offline bounce, that is.

Unless you have ironclad reasons to bounce realtime (such as using external sound modules), always bounce in offline mode.

I'm supposed to be working on music for a show and yet find time to make silly graphics, hmmm....

Think of the Buffer as a Digital Audio Bit Bucket, your computer's CPU needs to keep the bucket from emptying, the smaller the Input/Output Buffer the less time and the harder the CPU has to work keeping the bucket above empty. If it the buffer does hit empty you can get a system overload and/or audio artifact. Since the CPU also has to provide processor cycles for all virtual instruments native DSP effects and all in Real Time, you can see that I/O Buffer size is an important setting. There is also a side effect involved. The larger the CPU buffer the more time your computer has to work, however more latency is introduced into the system. This shows up as a slight delay when monitoring a voice/guitar/instrument running through Logic's audio engine, it can also cause a small delay when playing virtual instruments from a MIDI controller. Most MIDI/Controller work can use a 256K buffer, audio monitoring w/Logic effects needs a 128 buffer. When mixing/listening and not recording the buffer can be set from 256 on up.