I personally would never put a halter on a foal & leave him to get used to it (not sure if that's what you're meaning with your last post?) None of my horses wear halters when they are turned out (nor when they are kept in for that matter!)--they are haltered only when I am working with or around them and they have supervision. As for haltering a foal, I just make pets of the babies, and then when they're about a month old I'll slip a halter on & "lead" the foal around for a few minutes. Usually the foal is used to being guided along with my hand on his rump, or maybe on his shoulder--and so when I add a halter it's pretty much the same thing, I'll hold the lead rope in my left hand & guide the foal along with my right hand on his rump or shoulder. Sometimes I end up putting a rump rope on for some lessons, but sometimes the foal just picks up leading and we don't need to bother with a rump rope. We start in the corral with "mom" and then start going out in the yard for longer walks. We don't tie foals up hard & fast; we usually start by taking a wrap around a post if the older foal needs to be restrained for something, like hoof trimming or a needle--someone holds the end of the rope so that if the foal were to get violent at pulling back he could be freed in an instant. Generally it isn't necessary, because I'l be right there to push him forward. We progress then to tying, so in time the foal will know how to stand tied for hoof trimming, clipping, grooming, whatever.
As for clipping, I do clip my foals. I don't shave them, but I do give them a rough clip with the hair. I wouldn't clip if the weather is cold, of course, but we can get some very hot, humid weather in the summer, and foals can get heat stress in that kind of weather. I prefer to shorten their coats to keep them more comfortable. If they're tame & used to being handled, foals generally don't seem to mind clipping too much. Many of mine like it. The one summer we had 4 foals, and when I'd go out with the cordless clippers all 4 of them would crowd around me, fighting over whose turn it was to be clipped first!