Will the style of this years exam be similar to that of previous years?
Is it sensible to use past exam papers to revise with or are you going to change the whole format?
It's "answer 3 questions out of 4," as in previous years, yes.
I haven't actually seen the past papers from recent years, but generally, yes -ish. The material is much the same (mostly). Probably the tutorials are a better guide than past papers, though.
(As you have probably realised, I didn't take the course last year. I've followed the same syllabus, but the emphasis is probably a bit different.)
(And yes, I know this isn't a very useful answer.)