Agree with everything snowbrdr033 has said. Sounds like your biggest issue/need for the lift is to gain clearance, not maximum flex. The spacer lift will do this just fine and save you some money. If you can afford a full suspension setup with shocks/coils, then by all means do it. Just don't feel like you have to have it based on your needs (based on what you've posted so far).
UCAs are a nice addition at 3" lift, but not required. It all depends on the route you take. They made a big difference in the way mine handled (with 3.5" of lift).
The diff drop does very little for the 4th Gen 4runners. It really doesn't help the CV angles and isn't worth it IMO. The CV angles are fine with 3" of lift, and it just doesn't seem right to lift the vehicle only to lower the diff.
Those tires are boarder line most likely. I think you can run them without the spacers, but spacers would really improve the stance. Another thing to think about, you'll need a body mount chop to clear them along with a decent amount of trimming.
If you haven't already, read the suspension sticky at the top of this page. It will give a lot of info on the various lift setups, tire sizes, etc. May also help you narrow down the type of lift, and give you an idea of available options.
When buying a 4runner, be aware the some are equipped with a hydraulic suspension called XREAS. This limits your options for a lift. You can ditch it for aftermarket shocks/coils, but it's harder to find a shop willing to work with it. If you're doing the work yourself, it's not a big deal. All Sport Editions and some Limiteds come with the XREAS. More info on this is in the suspension sticky.
That said, I love my v8 4x4. To be honest, there have been a several recent posts about head gasket issues on the v6 that really have me concerned. Considering the number of 4runners out there, very few have failed. However, there are more issues that members have posted about here than I feel should be normal.
