Let's see... the PowerBook & Portable AC adapters are switching supplies, 7.5 V at various amperages. It seems the Portable's circuit can withstand 9 Volts input, because some people have run them from 9 V adapters without smoke. I haven't tried that myself. A PowerBook 100 adapter is fine for all purposes, including battery charging inside the Portable or in one of Apple's external battery charger trays. Just check to be sure it's putting out 7.5 Volts before you use it, as some of these old adapters have gone bad and put out more or less than the designed output.

The funky screen patterns are typical of a portable which is having power supply problems, either noise on the power busses due to failed capacitors, or problems with the power source. That's also what the screen of a backlit portable whose voltage regulator is failing looks like in the initial stages of failure. Can't help you with error codes. I suspect you're just seeing random errors due to flaky power.

Good luck bringing the old girl back to life!