1983 Magna

I have been riding it almost everyday since I bought it this spring and it has been running great till now. I cant start it unless it is in neutral and the clutch is pulled in, it will start right up then though. If I then release the clutch the guage lights all come on and the rpm needle starts going haywire plus the bike acts like it is about to die. If I try to open the throttle to rev it will rev but really choppy and when it idles down it backfires. One more thing, after starting it up the other day and running it till it was warmed up, I went to shut it off and truned the key back to lock it and pulled the key but all the gauges and lights were still on, weird. After messing with it for a minute I got them to shut off but dont know how. What is going on with my bike? I justwanttoride!