Should I get the A321 or B757?
Why do you keep buying 10 more planes right after you recieve 10 planes?
Should I make my foreign hub last to open?
1. Depends if you need range. If you want to fly inside the US, the A321 is the best. If you are planing trans-atlantic, the 757 is best.
2. Yes, if you can afford it and use them.
3. I dont think its worth building a foreign hub, unless its close to your home continent. Try Central America, but not any further... (thats where an A321 can get to)