It's not a bad job. The intake manifold comes off in a matter of minutes. The worst part of the job is getting the timing cover off and making certain the valve train stays in time during the reassembly. Make sure to follow the Ford procedure on the head torquing sequence and use plenty of fresh oil on all threads during installation. I believe the heads need to be torqued, backed off, then re-torqued several times. Just follow the PDF procedures. Not a job for a backyard mechanic, but it's not rocket science either, especially if you have the proper tools and a drivetrain manual.
The gaskets on the exhaust manifold are re-usable. That being said, if he's got a leak it probably needs tightening unless he has aftermarket gaskets from a set of headers. One side is an hour job if you know what you're doing.