1. I'd say both are about the same. The biggest difference is more legs, shorter flights on the 145. Days off are roughly the same I believe. If you like longer legs and doing fewer per day, 175 is better.

2. They pay rates are the exact same for both aircraft. This website doesn't really reflect that. You're paid based on your seniority which boils down to getting 145 pay until you're extremely senior (like getting close to flow senior) then you move up to CR7/175 pay. Regardless of what you actually fly. So figure for a new CA $67/hr at 75 hours a month of RSV pay. If you wanna figure per diem, it's $1.90/hr tax free at 200-300 hrs a month. That will give you you're base pay. Beyond that, you can pick up OT on 3 of your days off while on RSV. That's paid at 150% or 200% if they're short. But...getting awarded OT is based on seniority. There isn't much OT to be found on the 145 in general and there's not a ton that a junior CA on the 175 is able to get either. I'd say, figure maybe an additional $1k a month if you pick up OT and get lucky enough to actually score some OT if you're super junior. But keep in mind, year 2 CA at Envoy makes $67/hour. A year 2 FO at EDV is making $60ish/hr and the Republic TA is rumored to be even higher. A year 2 CA at EDV is making over $90/hr and Republic CA pay will probably be somewhere closer to that ballpark as well. Republic's TA details will be public Monday. Keep those rates in mind. They are not insignificant.