need help with eletrical issue

[zach 03 gs300]

Okay so i own a 192xxx mile gs300 its an 03. This past 2 weeks its been missfiring, i think its an o2 sensor. Thats not my real issue. I have a battery light that flashes on i just replaced it too. Then i have an airbag light that comes on an goes away, at the same time my gauge cluster flashes on and stays off for a random amount of time. If i turn on the ac the battery light goes away and the air bag light goes away. Also if i try to use CC it wont work unless i turn on the ac. Also my check engine  light is on. Please help i was considering taking it to a lexus dealer to get dianosed. I dont really want too becauase im an automotive student this would be a good learning experience, but it seems a bit out of my league. My guesses are theres a short in the ecu.

[TrevC]

With that many electrical faults occurring, I would start with checking the battery for condition....if in doubt, replace the battery but check all the electrical terminals (security, condition) and earth leads first.

[zach 03 gs300]

 QqI already replaced the battery that was the first thing i did. I found out if i get the battery light on, i can turn off the car and start it up again it goes away and doesnt come back untill i restart the car. The ac actually has nothing to do with it either that just happened to do it as i used the ac. I have a video of what its doing ill try to post it.