I am a newbie so HI! 
I need to know how often should I have my transmission drained and coolant drained? Does the coolant have anything to do with the AC? My AC just went out. It just blows hot air (like some people) and I am wondering if it is just the freon. I have a 94 Toyota Forerunner. Thanks for all your help
Typically, those fluids are changed at a 30k service, but rather than take my word for it, you should follow the Toyota Maintenance Schedule that came with the vehicle (it is contained either in your Owner’s Manual or in a separate booklet). The factory maintenance schedule will give you the correct information on those procedures as well as all other service procedures for your vehicle.
As to the coolant, that does not directly affect the output of your A/C system. If the A/C is blowing hot air, more than likely the system needs to be recharged with refrigerant.
If the refrigerant has leaked out of the A/C system, you will need to have the leak repaired before it is recharged.
IF the owners manual is not available ('94?) call a dealer for the maintenance schedule.
Re: timing belt replacement, etc.