1) What is the minimum height I can site a Bat boxes on the trees on my plot?
If your site is free from public disturbance, there probably isn't any minimum height, but on the whole, the higher the better. Try the most convenient height that you can reach with your ladder.
2) As far as I know there are 9 Species of bat in Scotland but which species of bats are the most likely to use the Bat boxes?
Long-eared and Pipistrelle
3)What is the best direction that the boxes should be sited on the trees i.e north,east,south,west facing?
In the arc between south east and south west. If you have plenty of boxes, a few facing north will provide an extra set of climatic conditions.
As well as putting up Bat boxes my main project, I also hope to put up a few Bird, Squirrel, Owl & Insect etc. in my small woodland also.
Be aware that squirrels and owls may interfere with bat boxes!
4) What are the most common types birds, Insects & animals that I am likely to get in my woodland so that I can plan what to put up as well as the Bat boxes.
How long is a piece of string? Best to do some survey work to see what you have, not guess what you might have. 
5) Can some of the other boxes be sited on the same tree as the bats boxes if so which?
Best not to put bird boxes close to bat boxes - you will get tits and others nesting and roosting in your bat boxes, and I suspect this may be more common if the two types of boxes are close together. Keep your owl boxes (if any) well away from bat boxes!
henrya