Leon,
As center said they are not required to give you any sort of leeway for the reserves. If you get into a flexibale unit, usually filled with airline pilots, the unit will work around your airline schedule. As an FO with Cathay you get 42 days of leave per year and can request certain days off if you put in the request early enough. This will allow you to make any mandatory drill days you need. Make sure you have very little chance of being called to active duty because the company has ZERO obligation to have a job for you when you get back. A training command slot is perfect.
As far as the company itself goes, it is a very good place to work. However, you must be prepared for the shock of going from military to international, heavy flying. It won't be as bad for you after C-130's, but for a single seat guy it continues to be a huge eye opener. Almost nothing from the military translates, but if you get the chance to fly here the pay is awesome, Hong Kong ROCKS, the 744 is amazing, and the people here are fantastic. The training was very straight foward and the instructors very pataint for the most part. I'm based in LA and am moving to San Deigo. I could stay in LA as long I want, but the best pay and trips are out of Hong Kong so a move here is on the books after my freighter "tour", can't wait.
Be prepared for a very hard interview and a long training cycle, but the it is VERY much worth it.
Cathay is recruiting like mad as center said so get your package in.