The door shouldn't be much of an issue. If light comes through there, just a bit of weatherstripping will do the trick.
For the skylights, you can make some sort of drawer so that the panel slides sideways into place. For the panel itself, you can use pretty much anything. Black corroplast comes to mind. So does black painted corrugated cardboard. If you laminate the cardboard so that the corrugation goes in both directions it will become super robust.
If you want to go for cheap, you can also make some sort of "hammock" out of blackout material. If you staple some felt to the side of the skylight in a way that the hammock will rest on it when drawn tight, it should be OK.
Now for the door to the house, I would definitely go for curtains with some pull backs. If you don't want to damage that nice door, you can always hang it on the door frame...
One thing I did in my garden shed a long time ago is just nail a block of wood on each side and hang a piece of wood on top of those. When you're done, you just remove the rod and everything is back to normal (yes, I had curtains in my garden shed)...