You won't need heel straps as a beginner, or at all really, they don't encourage good technique and really only benefit someone that is just learning to pop or jump. But if you think it will help Liquid force make some nice pad sets that include them.
As for a good board you need to look for a intermediate board between 134-138cm and around 41 cm wide. Boards that come to mind are the Tyro or FR from cardboards which are cheaper than most boards and have a 3 year warranty. The next board is the T5 from nobile it is probably my favourite free ride board, the x ride from north would work well or many other brands have very similar boards. Good flex, forrgiving and easy planing is what you are after for upwind fins around 50-55cm will help, most intermediate boards come with this size. Get on different manufacturer websites and have a read up on there boards, do some searching and find some reviews, then try and demo what you think should work well.