Carcharias

I am going to Roatan in a bit and have some questions. I've been doing
web research but am seeing some contradictory information and was
hoping you could help.

1. Can I get by with dollars my entire trip (assuming I bring lots of
small denominations)? It sounds like it's a hassle to exchange money
and I can't do it in advance as I'm not finding anyone who can provide
the Honduras currency.

2. Are there grocery stores there? I'm just going there to snorkel and
would like to be able to just buy groceries and save money that way.
Not interested in dining out or bars.

3. Do you need any kind of visa? I had heard there was some kind of
change recently but am not sure what it was.

4. What's a good guide book for Roatan? As mentioned, I'm mainly
interested in snorkeling and things more nature-oriented.

Thank you in advance....