You'll need an alignment, but that's it for changing out that piece.
Not to rag on you but in the time since you last asked questions and now you could've done a good amount of work or at least research. Going down in lift is much easier than going up. You'll just have to remove/replace the parts we told you about, and then from there it's just adjustments. Pinion angle is fairly easy, but can be tedious. Track bars will need to be adjusted too to center the axle, and then the alignment like I mentioned. I agree with
@tnjeepguy, take it slow and check marketplace constantly if you want parts for cheap (it's how I've built my rig so far). Everybody in here I'm sure has multiple stories of rushing through an upgrade/buying what the first guy told them and regretting it. At this point all I can recommend is to just start tearing into it and try and understand what you're doing as you do, it's the best way to learn.