I had the same issues as you. No power with the key on. I tried all the suggestions. Clean ignition and kill switches, clean the starter etc. What it was in the end was a bad/intermittent main ground wire from the battery to the frame. I made a new one from some 12ga wire and new ends...Eureka! All was right with my world.
As to the starter turning with the key off...That comes from trying to start the bike with a low battery. one of the relays (loadshed-starter?) gets stuck or welded together and the starter keeps spinning reguardless of the key position. Some say you have to replace the relay but I found a neat trick on these forums. Pull the battery out, charge it up fully, reinstall the battery and attach the ground wire. Ignition key on and the killswitch in the middle position (like you were going to start the bike) Then touch the positive wire to the battery terminal and at the same time hit the starter button several times. this broke the relay contacts free for me and I have put many miles on since. Good luck!