Any of the boats in the Orkney dive boat association are fine enough, my favourite is Karin, flat dive deck, plenty of space, any gas on request, dive lift - like most of the boats a converted trawler, so basic by US standards. The boats will be booking up by now, so you'll need to do something soon for a peak season booking. - off for a long weekend there tomorrow
Wrecks - cruisers - the Koln, Markgraf is stunning - plus james barry, Tabarka and Doyle
Bars - there are only 3 - all within 200m of the pier, all do food - food is best in the Royal, best beer choice in the Flattie. The Ferry always used to be the place to be, but it's a lot quieter now. There's a nice cafe, Julia's which is nice during the day. Hotels, again the same choice, Stromness Hotel was OK, Ferry was very noisy - if you don't mind basic, do a liveaboard and enjoy a sleep in in the mornings.
Scapa Scuba are the padi centre, good store attatched, I've watched them training over the years, and they have high standards - connected to the Radiant Queen if there are only a couple of you