You're likely going to have to remove some facia boards/trim to get the old one out - exactly how many and the level of difficulty will depend on your RV's design. I don't know how your current fridge is secured, but it's probably screwed into a wood frame. You'll need to cap off the propane line - won't be needing it anymore.
I have no idea how much wood-working will be needed to get the new fridge in, secured and looking nice, but make sure you don't install new facia boards or trim too close to the fridge's door frame. If the front of the fridge is flush, or nearly flush with the trim, the doors may hit it when they're opened.
You'll need an inverter to invert 12 volts to 120 volts, because res fridges only run off AC power. The size of the inverter will depend on how much power the fridge uses. Don't go overboard here, modern fridges are pretty efficient, and big inverters consume more power and need more battery capacity.
I don't know how much battery capacity you have now, but if you plan on boondocking, you may need to increase the AH capacity of your battery bank. Res fridges always need 120 volts to operate. If you're always plugged into shore power, and rarely boondock, you may not need more AH capacity.
Kev