Yes, Nucs from all of the regular suppliers around here sold out a long time ago also but there are usually a member or 2 from various clubs that start some nucs for their own use and also a few to sell

Why is it important to retrieve the cocoons and cleaning house each year? The emerging bee have been inside that tube for the whole year: From egg to larva to pupa to adult bee; once the bee have emerge there will be a lot of debris left behind in that hole: empty cocoons, faces, mud and a lot parasites, mainly pollen mites. For the bees to reproduce in great numbers is important to start out with a clean nest each year. To break the cycle you need to hang a new house next to the old one and partly blocking the entrance of the old one to discourage their re-entry. Most of the bees will pick-up nest in the new house by virtue of been clean, therefore more attractive. The only way to retrieve the cocoons is to unfurl or cut open the tubes, been careful not to damage the cocoons. Most years timing their emergence is all guess work; I would not recommend to hold them back beyond April 1st.

If you're able to leave them (and continue working them, there), that's what I'd do for now. I'm not sure when your main honey flow is, but I'd guess the hives are heavy (or will be shortly) with the surplus honey you want. Generally, to answer your question, I'd say the best time to move them is during the late Winter or early, early Spring - the bees aren't flying; the population is the lowest and most of the heavy honey (food) stores have been consumed. Plus, you may find it to your advantage to combine hives if you have any 'dead outs' from the Winter at that point. You are right to be concerned about loosing the field forager population if you try and move them now. The problem is your distance - too great to move the hives, little by little and not great enough distance to move them without the bees re-orienting to their old location.

I was going to say, most likely not honey bees in compost but when you say composter, ...if it's some sort of encloser/barrel/box etc. then yes, honey bees like them to set up new colony. Turning compost now would kill them,...let them be for winter, most likely, it'll kill them too without any protection in our harsh winter. If you want to try to save them,.. put sheets of fiberglass insulation into black trash bag and tie with strings around, do it now. The entrance,..probably too large, you can cut a reducer, Styrofoam/plug, drill a hole not bigger then a dime. No guarantee,..if bees moved in later in the season they don't have enough food store build up to make the winter, you can feed them now, mix white sugar, 2 to 1 with boiling water water then put into a container, [put about 8 foot or so beside the hive] put a bunch of wood stick on top so bees don't drown. A Queen is with them all the time, she might still have some brood going/new bees, these new bees are also important for winter survival. Come spring and they made it then they can be re-located by a beekeeper. Picture would help.