I've done over 100 dives with them over the years. you will have a blast. I dove the entire time with no wetsuit (28-30c) so bring a 3mm max. depends how big of a wuss you are though. When you go be sure to mention Oren says hi. Try to dive with Dan, DMO, or Neel they are awesome. Their night dives are done around 6 so you will not need a super light. No need for a SMB your guide will have/use one. Snorkel? I guess if you want during the SI they stop at the islands. If you want to be a big hero TIP ahead of time. I usually give the crew box 1000bht ($30) and my guide for the trip 1000bht. A lot of Europeans are cheap and don;t tip so fi you do you will have an even better experience. Bring a Micro fibre towel packs better and dries faster.