Hey Luie,
Your mind is working good directions and you're asking good questions. We mostly hunt geese with small, mobile setups, and they might work for you. Here are the key points:
Watch the pattern of goose behavior for a day. Ideal is a morning "fly out" when they leave for water or whatever, then come back to the same spot. Basically wait for them to leave, set up, and wait for them to come back. If you can do a good enough job of hiding, shots are really close.
We use 3-6 oversize shells. I don't know what's current, but mine are Big Foot brands and the geese take them for the real thing.
A call is really important, because the returning geese will want to greet the newcomers in "their" spot, and they'll expect conversation back. Get a tape and learn to call, but don't call too much.
Expect the geese to circle out of range, then a few of them to drop down to join your spread. That's cool, and go ahead and shoot them, rather than expecting to wait for the whole flock to come down.
We use fine camo mesh or web to hide, the kind that's pretty closely woven but you can still see through. It usually won't work by itself, but lay down in any kind of fold or depression in the ground, pull it over you, then pull a few pieces of vegetation onto it to break up it's outline. Cover yourself completely and look through the mesh to watch the birds, rather than exposing your face and hands. I own three colors: Dark brown, white and two-sided green/brown camo. The pieces I have are roughly 8x8' and wad up to nothing in a decoy bag. I just swap between them, depending on what's natural in a spot.
Hide out to one side or the other of your decoy spread, rather than upwind like most people do. Geese will land into a breeze if there is one, but if you're upwind of them, they're looking right at you as they land. Getting off to the side gives you side shots, which I like better anyway. It's a fine point, but sometimes it helps to put one of your decoys a little apart upwind of the rest, just where birds would "expect" hunters to be hiding. In some cases it really helps to reassure them.