The business situation in Tbilisi

I would like to know the possibility of working there in Tbilisi for expatriate who doesn't speak Georgian language.  And I would like to know the average income of mid-management employee.

Unless you know Georgian language you're mostly out of luck, unless you can find some international company that might hire you that is. The average income in Georgia is around 300-400 lari which is roughly 150$ as of right now