What do I need to know about lending? What is considered a sound ROI? What questions do I need to ask the realtor? Can I see property income from prior owners?
This is an out of state purchase. It may be a pipe dream right now. But we have always wanted a beach home, but to be used as a rental also.

If the property is on the beach, it is likely a Condo hotel, or called a Condotel. If the property allows for short term rentals under 30 days it will be a condotel which are very different to finance then a typical condo. Condotels are NOT eligible for conventional financing so rates/terms are not as good and more down required. But, we finance them all the time so they can be done but you have to understand it is different.

Most Condos I see have a pretty high HOA fees that would erode your profit.

Speak with other investors or marketplace participants in the area to set expectations for market rent, typical grm's, typical rent/bedroom. I personally would not buy in a market area that I am unfamiliar with, without consulting someone who has skin in the game in the same market area.

Speak with a loan officer to get an understanding of the financing situation.

Speak with the county tax assessor to get an idea of what is/isn't permissible per zoning, and to establish the legal definition of the property as a Condo/Condotel/Townhome/Apartment/etc.

You can get all the info you need in less than 20 minutes, with 2 or 3 phone calls. I do it all the time.

ETA if the underwriter and/or mortgagee you speak to has a 216 (operating income statement) on the property you are interested in, from a prior appraisal(s), they may or may not be able to share it with you.

What they said.

I'd also get my hands on the HOA budget and financials.