I don't have experience with the Global Freestyle.
However, here are my answers to your questions.
1. as long as your plane weighs within the limit that the factory suggest, you won't have problem. If the plane weighs more than the maximum, make sure that you have plenty of power. OS 91 should be fine.

2. use your dual rate or triple rate settings to start at lower rate of the actual recommendation by manufacturer. Stay safe at the first flight. There is the test flight setting in the manual of Freestyle, I think you can set it as low rate first and sport setting as high setting to start with. If your radio has exponential, use it. Exponential function helps a lot expecially at the first flight.

3. Seal all those hinge line with trim tape, silicone, or covering materials. If the control surfaces are very large, you can also counter balance them to reduce strain to servos and linkages.

4. As long as you have good quality servos without any worn gears in them, you won't have to worry about it much. Just make sure the servos have enough torque to move the control surfaces.

5. Better landing gear? if the mounting is supported good, and your plane is not too heavy for the supplied landing gear, why bother looking for another one? I don't think there is any better landing gear for performance. If you are talking about the weight, then there are several carbon gears available, but cost are higher.

Hope this helps,