To answer the question (and do check the web site as I am going from memory) the downwind side of 12 is to the south so if coming from St Catherines you are probably best to join crosswind. You could join right base but you do need to be aware of traffic into Sandown (the approach is relatively close).
It is worth noting 12 slopes downhill and the land rises to the threshold. There is a tendency for the novice pilot to land long and depending on the aircraft the runway can end up all too short! (with the ground rising over the caravans to the cliffs at the other end).
Landing the other way it is worth noting that in a strong wind, particularly with a cross wind component, there can often be pronounced sheer and turbulence as you come over the caravans and all the way down to the runway. It is one of the few places over the years that still has the ability to catch me out and has done so on more than one occasion.
In my opinion the Propellor Inn is sadly truly dreadful - give it a miss. The Crab and Lobster is a great deal better under new management and worth a visit - particularly for the views. The cafe at the Lifeboat station is a treat for really good seafood. Sleepy Hollow is a very special treat but you need a car. Car hire is easy and cheap from Bembridge - they will even deliver to the airport for around £30 for the day, and you leave the car back at the airport on your return. Treat them well it is a very good service they offer.
The coastal path isn't closed although some sections have fallen over the cliff and you have to work your way around - there is one section that occasionally has some tape baring your way, but you can duck under. You can also walk along the beach at low tide but at the far end before freshwater bay there is a scramble over the rocks if the tide is much above half way.
Personally I have walked across the runway many times. Keep your eyes peeled, it is rarely very busy. After all there are plenty of airports with public footpaths crossing the runway / threshold!
Enjoy, it is still one of the very best places to visit in my opinion especially on a hot Summers day. If you are there for a day hiring a car is really well worth it if you fancy a little touring around and generally having a good day out.