Loads of options. I would say all resorts will offer a village visit and many are close enough for you to walk to the village. Casula visits to villages are not a great idea as it is polite to follow local custom which is far easier with a guide / host. You will often find theh staff at a resort will offer to take you to their village. That would be a great way to go usually. They won't want payment, but an offer will usually be gratefully received. Organised tours are usually charged for in some way.
As far as the diving part, it depends on how long you have, your budget and type of diving you want. Some of the best spots are a little further and may well involve an internal flight which limits yor last days diving and increases costs, so if you are here for 5 days, maybe best t stay on teh main island of Viti Levu or a resort that is reached by boat, like Beqa Lagoon Resort. Longer stays let you get up to Taveuni in the North or Kadavu n he South. The further away from Nadi you get, the more 'real' the Fijian village experience would be.
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