It’s predominantly from your Application. A pass is a pass for your RT. Your additional info you’ve submitted, reasons for choosing particular department, any previous work experience that can relate to RFA. Not necessarily sea experience but teamwork jobs, working to deadlines. Any voluntary work, involvement with cadets either as one or a volunteer. It’s a whole picture of your work experience up to now. Or if your nipper what have you done that sets you apart from other 18-20 yr olds.
This forum has a huge amount of info, advice, tips, etc. But regulars on here are fed up repeating stuff!
Use the search function top right of this page. It is really good and will take you to pages and pages of info. Just use keywords or phrases.
Once you’ve trawled that come back and ask if you haven’t the answer.
From what I can see and I believe it to be the same if not, then similar within the Engineering Dept.
As for the rate of climb, that I don't know, although if I was to go out on a limb I think a reasonable answer to 'Within 10 years time' would be a Leading Handing. But I could possibly be way off with that and hopefully someone currently serving or with greater knowledge can confirm for you.