How to prepare bed for printing ABS filament? I have never used ABS filament before, so my question is, how do I prepare my glass build plate for printing ABS filament?
My second question, is, after you have prepared it, and have finished printing, can you 3d print with other plastics, such as PLA after?
ABS can be a problem to print, but there are generally a couple well established methods to prepare your glass bed, which might be combined for best results:

Heated bed. A heated bed is almost a must for ABS and would be set to about 75 to 90 °C for most printers. Often this can suffice on its own, but keep the bed running for the whole print!
ABS-Slurry. One of the best functioning adhesive helpers is ABS-Slurry, which is made by mixing a little acetone with as much ABS filament as it will solve, then applying a thin layer of this compound to the glass bed right before the print. It will stink a lot, but it most certainly will offer one of the best adhesions you can get and might even prevent Warping due to the stronger bond to the bed.
Rafts. You might want to add a raft of at least 2 layers under the print. The Raft can be removed in the end, but it increases the surface area and can often help to reduce the chance of warping.

Now comes the good part: you just need to remove all the ABS residue and the bed is ready for the next preparation for any other material. This can be done with a scraper blade quite easily, maybe some Acetone and then alcohol if there are some really nasty bits.