As I think I've said to you before, you should ask all these Qatar based questions here:
People employed by Qatar might look there more than the Wannabe thread, so you are likely to get better replies! Ask there what the interview process is like.
As for the critera needed to apply, its all on their website:
Minimum age of 20 years
Minimum arm reach of 212cms (on tip toes)
Minimum high school education/ O levels, with fluency in written and spoken English (ability to speak another language is an asset)
An excellent level of health and fitness
A willingness to relocate to Doha, Qatar
Ideally, having an outgoing personality with good interpersonal skills and the ability to work in a team environment is an advantage.