If you go to Sprinkler World and take a layout of your yard they will help you design a system. I think there is a charge for the design if you do not buy your supplies from there. If you buy your stuff there the design is free. The actual install is not bad if you are a handy guy. Trenching can be a pain. You can rent a trenching machine from Home Depot though.

I would have someone else do the grading. It is worth it to pay someone who can know what they are doing, especially if you have a good size yard.

Laying sod is a lot of work, but not technically difficult.

All that being said, I paid to have my sprinklers and sod done. I didn't have the time and it only cost me a few hundred more to have someone else do it that could come back if it wasn't done correctly.