PVC pipe cutters will save you from having to deburr, and it's a lot easier/straighter/faster than a hacksaw, especially if you're eyeballing and trimming down lots of cuts for fit. An irrigation supply store will have a pair for around $10. Lowes has some but their metal ones are $20 or more, and no better. One plastic pair will last forever if it's only used for odd jobs.

http://www.sprinkler.com/buy/item/pipe_cutters/4554

<-- an example of the kind I mean.