Dazed&Glazed;
Ref package, applicable to both Instructors and Controllers do an archive search ... comprehensive and articulate information available.
1) Assessments are dynamic, but realistic, promulgated to guage if you are suitable to be trained on a discipline - not to embarrass or shock you and it is conducted with that in mind. Pass rates are irrelevant, but as a grab I would place it at about 85 to 90%
2) Managements decision on placement and projected surplus.
3) Again - an unknown, but generally they do try and keep you if not close, then at least closely located to a main road.
4) You need to clarify that with your recruiter or whoever you are currently in communication with...any answer on this forum is tantamount to speculation.
5) Standards are high as Doha is a rapidly bulging hub and mutual respect exists between all professionals. As a footnote - without being patronizing, how you integrate with your Instructots / future colleagues rests in its entirety with YOU ... if you are a serial Whinger and Whiner ...well what can I tell you?? There will be obstacles and times when your frustration seems like an everest ... this where your character takes centre stage. Remember this, nobody here doesnt want you here ... we all want extra staff so by default we do want you and your skill and experience...its up to you how you deliver yourself as a person and your skill as a professional.
6) Just a gratuity...but a good one. Do the archive search.
All the best for the assessment - Ciao.