Do flames emit UV?
Yes, but how much UV depends on what's burnin / how hot its burning. Otherwise they mostly put out IR.
We use UV/IR combo Flame detectors at work for this purpose.
IIR, hydrogen flames can emit enough of their energy in the UV for that to be a serious issue - both direct human exposure, and degradation of exposed surfaces and equipment.
a little but not much, from my quick look online.
lived with candles and kerocene lanterns, etc for years and the odd bug will go nuts and spiral in, but not very many
but all in all, there are way less bugs everywhere now
No but they emit smoke