Real Estate Question: Owner as agent--how does this affect a transaction?

I saw a house listed that stated :owner as agent. For some reason, it felt a bit “intimidating” to me in the sense of attempting to put in a bid on a house. The house seems a bit high for the area. It is not in a small town and it is much higher than real estate of that age for that area. (It’s an older house). But I really do like it. Because I keep finding houses I like that have this listed, I would like some advice.

1. Where can I find out what the house sold for originally? (If I don’t live in the area?)
2. How (in this crazy market) do you calculate an offer (I don’t want to offend the seller especially if they are an agent.)
3. Do I get someone to act as a “buyer’s agent” when approaching an “owner agent”....or do I contact the owner/agent directly to handle the deal? ( In other words, will that help with the negotiations/price,etc. I would think that it would put me at a disadvantage?)
4. How do you arrive at an offer price? Is there a formula?

I would appreciate any help and/or advice.