[Crex]

Sorry 'bout that.....want to see my AARP card? Says I can forget anything (and I'm getting a lot of practice in).
Most makers I know use their platens constantly. I used my first home-built grinder for years without one and taught myself just using a 10" wheel. That was back when I did stock removal. Once I got serious about forging my blades having a platen came even less important. Then, after about 35 yrs. of abuse my old home-built's bearings got sloppy. Lucked out and bought out another maker's shop and wound up with a practically brand new KMG with all the fixins including a great platen w/glass. I still experiment with it from time to time but just don't use it much at all except when rough flattening handle material as you mentioned - old dog thing.
Wish I had a window that near my grinder for the light alone, but sounds like you got it working for you ventilation wise (I have a vac system). Sparks issue is one of those things one wants to learn early for sure.
At least now you have something fun to do while you wait for the spring (summer) thaw out there.