Since i was also in same boat i can share my practical experience.

1. can i pay my monthly due from there to my account, is this ok or not (is CBQ will close my account because im not at qatar)
- Yes, transfer money to CBQ, your account will not be closed.
2. if i continue paying my loan monthly, am i having problem in GCC airport
- No problem, unless you miss few installments and you are not contactable and then CBQ files case on you.
3. can i return Qatar after 3-4 years?
- If your installments are coming on time, no issues.

Please note: no police or airport knows about anybodies loan unless the fraud case is reported against someone, also bank is concerened with the money not in which country now u live in.

Hope it helps... All the best..