hi Bert
as a crofter myself I can only tell you what I know.
It depends where the croft is and who the landlord is, ours is the Assynt Crofters Trust. You need to apply for a croft and be added to the waiting list (if there is one) but you can rent a croft from whoever the listed tenant is if you can find them
you then have the croft rent to consider. Do you plan to stay in temp accom and work on the croft? Assuming its within reasonable distance of where you stay?
There are some issues going on at the moment regarding 'absentee' tenants but this takes years for the Crofter's Commission to sort, currently they are working on a list of people from 10 years + who are classed as absent, bearing in mind you should live within 32km from your croft, following link should be of some help to you.
http://www.crofting.scotland.gov.uk/faq.asp?q=32&catid=10if you are successful in obtaining a croft then you are issued with that particular crofts CPH number which you need to register any livestock you may wish to keep on the croft which in turn gives you the problem of fencing the croft. Is there adequate fencing/boundaries?
Anyway don't want to bombard you with info at this stage, research into the ins & outs of crofting is the way to go, its not as easy and straight forward as it sounds I'm afraid. An empty croft may not be in fact 'empty' so you need to find out.
Hope this helps