Hmm, I've never felt the need to inject beef, especially the rib roast...poultry, and, once in a while, pork, but never beef. Whole beef rib has a good balance of fat to muscle ratio and doesn't need much enhancement to taste good. A simple seasoning of SPOG (salt, pepper, onion, garlic) yields very good flavor. Once you inject, you no longer have an intact whole muscle meat, so treat it accordingly...see the heading in the FOOD SAFETY forum.
Hickory for smoke...toss in some pecan and/or cherry along with it, if you like. I have used 3 to 4 smoke wood combos and they were all good. Apple is a bit lighter than cherry, and pecan has a more pungent aroma and deeper flavor...hickory is sharp, but somewhat sweet. Mesquite is a very heavy, earthy flavor and aroma...I use it sparingly with any foods, and usually in combination with a few other woods.
I know that everyone has their preferences, but 165* finished temp for a rib roast??? I'm a 140*ish guy myself. 165* may yield a bit drier product in some areas of muscles of the rib eye, but overall, there's enough fat in there to hold up reasonably well. I can't vouch for what you should expect, because I never had the guts to take one that high.
KISS method for whole beef rib has never failed me. Simple prep: cross-hatch score the fat-cap, apply SPOG and rub into scoring. Smoke @ 225-250*F until about 5* below desired internal temp (carry-over will increase temp). Rest for 20-30 minutes before slicing. ENJOY!!!