This is one of the many contradictions I am seeing when learning about hardwood floors. Some say pre-drill, and some just use the pneumatic finish nailer with no predrilling...which is it? (Regarding quarter round, T-molding, other transitions)
18 gauge brad nailer. For any small pieces under 6", I usually add some titebond glue to the back and use a 23 gauge micropinner. The small pieces will split sometimes with the 18 gauge nails. You can pick up 18 gauge guns for 40.00 if you look around. I bought a Porter cable reconditioned gun for 40.00. Looked and worked like brand new.