Some answers to my own questions, after processing what's been said here:

1. The end stop. For others who may come searching here, it's actually called an "axis sensor" on the Flashforge USA parts shop. And it only costs $2, and for a creator pro you want the "regular" variety. Now – if only I didn't have to wait for shipping!!

2. The glass. They sell one on their store for $11. I bought one. They say it's 1/4 inch thick. Soon I will know whether it works as nicely as advertised.