The O2 sensor will get lazy over time, it won't necessarily trip the CEL. Depending on mileage it may be worth it to change.

You need to account for your new tire size when calculating mileage - your speedo and odo are now off w/ the increased tire size.

You got some responses to your paint color question on the ToySUV Forum, pop in over there.

4x4Wire's Toyota Section
1995 FZJ80 LandCruiser - 3 locking diffs, +200k mi, JD HIR's, 285/75R16 Nitto TG's
Olde North State Cruisers