Odd problem, electrical, battery discharging...ignition?

[brent95m3]

I just my 2002 Boxster S last week.

So last night while driving the battery warning/generator light comes on. It was late so I didn't do anything about it. This morning I go to start the car and its dead as a doornail, so I figure bad battery. I jump start it, and then go to buy a new battery. On the way there, the ABS failure light and the Brake Distribution warning light both come on. I clicked through them but they came back on and kept beeping upon accelerating (really annoying). The radio as well would restart itself. After a couple miles I guess the warning lights gave up and it just went to a check engine/service engine soon light.

So my theory/guess is this is the ignition switch/cylinder problem (hence the reason the radio would turn off/back on while driving and the warning lights would reset themselves).

Has anyone had anything like this and if so, was this the problem? What parts do I need to fix it assuming this is the issue?

Thanks in advance.