Hey Tele!
I had some LED lights similar to the ones you have. I used a couple of rubber insulated conduit straps for each that I wrapped around the highway peg arms. The nice thing about having these mounted low is that the approaching cars see a 'triangle pattern' of light, which stands out more than a row of lights, hence helping in the 'being seen' department. Plus, as mentioned above, this improved the 'side to side' visibility to the front of the bike. When my bike went down earlier this year, it broke the left highway peg arm off, and I haven't had these on since.
However, I have since discovered that the C-10 mirrors are each held on by a single bolt at the base of the rubber boot (with a couple of studs to prevent rotation of the boot). I'm sure I've seen at least one Connie that has stuck a mounting bracket betwen the boot and the mounting base, and attached extra lights there. Lights that are mounted higher will be more useful in everyday driving situations than lower ones, as pointed out in the C-10 Mods section. Lights that are mounted lower help more in foggy situations, I'd guess because light isn't being reflected at a near right angle right into your eyes (photonics experts feel free to inject scientific explanation here).
Looking at the federal regs, I believe there is a limit of 6 operating headlight/fog/driving lights facing to the front of a vehicle for onroad use. This covers the four headlight arrangement of older cars with separate high beams, with an extra pair of fog lights. So mounting four more lights on a Connie should be fine, and if you go with Murph's headlight kit at some point in the future, you'll still meet the six operating lights total at any given time. BTW, high beam activation is supposed to shut driving lights off, and I believe Murph's upgraded headlight harness takes this into account.
Offroad use is another story, you can have as many operating lights as you want once you leave public roads...
Keep in mind your amperage overhead on your alternator. The Connie's alternator I believe outputs around 400, which may be insufficient if you have a pair of 55W Hellas and some other accessories running. LED's have a much lower amp overhead, hence why I find them attractive. Several here have done the ZZR 1200 alternator upgrade to deal with this problem - good luck finding a good deal on one!
HID's are da bomb, if you can find good ones. I've seen some comments recently about some brands being less reliable than others, so do your homework.