Slice timing or not?
See the page on SliceTiming for a discussion
Realign and unwarp or just realign?
See the Realign Unwarp section of the MotionCorrection page.
Scripting your modelling?
The newer releases of aa allow scripted first level modelling, first level contrasts, and second level modelling. The first level modelling requires you to do a little coding, to specify your design. Unless you are the one neuroimager on the planet that gets the design of the analysis of their experiment exactly right first time, I would recommend this - you'll find it a little effort now for a big gain later.