It's actually pretty straightforward/simple and the only tool you'll need is a phillips heads screw driver. Open up your amiga and have a look. It's quite simlpe/straight forward/logical how to replace it when you look at it. As for CF vs a 2.5inch ide drive, as mentioned the main advantage is the fact its silent. You may find slightly quicker read times on a slower system too (although write speeds might also be a little slower).
Despite what many people seem to believe the 4gig drive limitation is more or less a myth. You can use larger drives with ks2.1 and upwards (maybe even older, but I cant say for sure). The main restriction is boot partition size.
