I've been three times each for about 7-10 days in 2018, 2019 and 2022. Planning to go again this year for a honeymoon (no pics).
You've selected a great location. West End is awesome, it doesn't have the white sand/blue water or big "resorts" that West Bay has, but it feels more "local". It's obviously still tourism based, and you won't be as bothered by the day trippers when cruise ships are in town.
As for your plan regarding SCUBA certification. I would look into seeing if you can do your classwork/skills at home online and at a pool local to you. That would leave only the four checkout dives to do with a dive shop on the island, saving you a lot of time.
You can certainly do the whole course on the island, but I think you'll enjoy your time a lot more if you come already nearly certified, with only your check out dives to do.
I've only dove with West End Divers, great shop. But for the most part it's a competitive enough market that most all of the dive shops will be just fine.
There's not much going on for local Honduran food, but do try a baleada, basically tortilla and refried beans.
- Sundowners is a popular bar with great views, ok food.
- Sandy Buns is a fantastic baskery/bbq/burgers sandwiches.
- Creoles Rotisserie Chicken is fantastic - you guessed it - rotisserie chickein.
- Gingers also has great views and solid food.
- Fancy/Luxury dining: Luna Muna at Igabari hotel. You can take a water taxi from West End.
Will post more as I think of things.