Yes, lots of circulars, Dans! Yes you could call them U-shaped when small, Mammyshaz, circular when longer
DPNs aren't a bit scary - just have a go, Dans! The trick is to use ones that are short enough but not too short - I prefer 6-8" ones for socks, preferably bamboo rather than metal - and to use at least 4 if not 5 so you're not all working round tight corners. And to not wear a woolly jumper while knitting with them in case you catch the end of one in the jumper you're wearing
(Fleecewife gave me that tip - and she's right!) In terms of not getting a big gap where you move from pin to pin, there are two tactics. I just knit across the next 3-4 stitches each row, so my DPNs keep moving around the tube row by row, or jaykay reckons if you tighten the
second stitch on each pin, that keeps it neat. (I haven't tried that yet, will do on the next tube I knit.)
I do hourglass heels, so that I can drop them out and replace them if they get too holey / undarnable (or so lumpy with darning they're not comfortable any more.) For the heel itself you would need to use short needles as you knit that bit back and forth, then rejoin when the heel is shaped. So if you preferred, you could knit the whole sock except the heel itself on circulars. If you like gusset heels, I'm not sure - jaykay would know, I've seen her knitting socks on circulars; mind on that occasion she was doing both socks together (toe up) so she could just keep knitting up the legs till her yarn was used up, which is a different thing again!
In the Twisted Sisters Sock Workbook, which is my bible for socks, they talk about a technique where you knit the heel afterwards. You knit the sock as a tube, then open it up at the heel, knit the hourglass heel and join it in with kitchener stitch. If you really hate DPNs, you could consider that?