If I rent an apartament for say $8000, will I still get the full $14000?
That's correct but I think you'd have to live in Tung Chung to find something that cheap.
How can one qualify for this additional assistance? Is it difficult?
Easy... basically you just find a house right up to the max allowance which now I believe is more like $26,000 then Cathay have to approve it. Normally they do but if it was a place in Tung Chung that clearley wasn't worth that $26,000 they wouldn't.
The allowance goes up in a couple of steps I think, but the main one being when it almost doubles after two years.