It seems unrealistic for them to ask what the precise passenger load range and cruise speed (exactly) of a RJ70 is, but if they do I want to be prepared!
Hi VirginGirl,
Just some friendly advice for your hopefully probable new career: If NATS give you a document and advise you to learn it, then learn it. I know it sounds blunt, but if the cruise speed of an RJ70 is given in the document, then they might well ask you what the cruise speed of an RJ70 is, and I don't think it is unrealistic at all. That's exactly what you'll have to do for the rest of your training; learn facts and basically a whole book (Manual of Air Traffic Services) almost word for word....best get into the habit now.
The question might take one of many forms (a range of approximate speeds, say, or it might ask you to order four a/c from slowest to quickest), but if you know the given figure, then all can be answered easily.
By all means absorb the advice given on this thread by those who have gone through the process before you, but who knows how often the motivation question paper changes? 
Good luck anyway....