for your bulbs, are you running both head and tail light? alot of people dont like running taillights but also forget that tthe bulbs work in conjunction with each other as voltage regulators.
find some higher wattage bulbs, usually in the "performance" section at kragen and the like.
the backfiring could be because the magneto may have slipped on the taper, or several other problems. Did it run fine pre kit and timing change?
i would re pull and reseat the flywheel for starters.
oh also i just saw you have no tail light. get a tail light, thats why your bulbs blow.