Hey Steve
Welcome to the forum!
The first thing is to direct you to the Editors Depot (link at the top of this page) where you will find more tutorials than you could ever want. Start with snYpir's OFPEC Guide: Making Missions and my own macguba's guide to mission editing for beginners.
Now, as to this specific problem. Firstly, its totally solveable. Secondly, lets just solve it for one chopper - you can easily add more later.
Create your chopper. Give it a name in its name field, lets say chopper1. Set it to flying (in the special field). Create move waypoints for it, making it go where you want. The last waypoint should be CYCLE. Place the cycle waypoint near the first one and that will make the chopper go round and round for ever. Yes it will run out of fuel in the end (after about 2 hours I would think): you could create a refuelling routine but lets keep it simple for now. In the On Activation field of the cycle waypoint write this
chopper1 setFuel 1
That means it will automatically get a full tank of gas for each cycle.
Right, now we have some subtleties to deal with. Landing and takeoff; and loading and unloading; and coordinating several choppers. For the time being, create another chopper and give it a route and a name and do the same fuel thing. Now, click on synchro at the top of the Mission Editor screen and drag and drop a blue line from one of chopper1's waypoints to one of chopper2's waypoints. Each chopper will wait at that waypoint until the other one gets to the synced waypoint: this means you can control the timing and make sure they don't bump into each other.
Unfortunately choppers are notoriously difficult to deal with. They have minds of their own. Landing and loading are slightly trickier and I suggest you get this all working and read a few basic tutorials before going any further. There are a couple of specific tutes on choppers and you should have a look at those.
OFP editing takes a little time and effort to get into, and it sounds like you are about to hit the "frustrating" stage but don't worry, it doesn't last very long. Come back here and ask when you get stuck.
Aside: you won't be able to make fixed wing aircraft take off automatically from that airfield: its a game thing and not easily got round. There is only one working airfield per island and the runway is always north-south. Just thought I'd mention it in case it's important.