So… I’m stumbling my way through this myself right now…
1. I’m not entirely sure as I didn’t think to measure anything prior to starting, but likely 2-3”. More if you switch to 08-11 torsion bar keys (factory keys, junkyard would be your best bet because there seems to be little information out there and most keys get lumped as 98-11 when in fact the 08-11 Rangers sat lower from the factory and the keys were all that changed). I can’t say how much drop you will get out of the 08-11 keys though, I don’t have a set yet.
2. Shocks may likely need changed. Not sure what to recommend yet.
3. Factory bump stops need to go. Should be a 10mm socket up through the hole in them and unscrew them. Ideally you’ll replace with some other sort of bump stop.
On my 2000 4x4, I’m still working on getting the rear squared away. I did an Explorer 8.8” rear and springs and kept it spring under like the Explorer had (unlike the Ranger). I cobbled together a set of Explorer packs with two extra leafs and even at that, I ended up with so much drop a frame notch would have been required. Drop shackles (the Belltech 2400 and similar which actually lift the Ranger) got me about an inch and a half of clearance to the rear bump stops. I’m also facing a pinion angle issue in the rear, but that’s a side note. Going to try a set of heavy duty Ranger springs next in the back, otherwise I need custom springs or to modify the hangers.
As to the front…
Initially I backed off the adjusting screws (with no weight on the suspension) something like 10 turns each. Then a few more turns after weighting the suspension and seeing that it still wasn’t where I was hoping to get to and when I put weight back on the suspension, I wasn’t any lower. I then realized I was on the bump stops. So I pulled bump stops and shocks then backed the adjustment screws until the torsion bar key was nearly against the adjusting screw plate. I’m still not overly satisfied with the drop for how low my rear is, so at this point I’m looking at getting the 08-11 keys and try to get the rear worked out. Right now I’m at like 3” of clearance tire to fender and I’d like to lose another inch if possible.