Can i order a piece of glass?

Yes you can

Yes. Lowe can cut glass. A glass shop may be a better choice depending on your specific needs.

I think it depends on what it's for. If it like a door or cabinet you should be able to.

Best places for plate glass is Ace Hardware or other neighborhood hardware stores like them.

Last time i was in lowes they only dealt in polycarbonate in store and as for ordering a replacement pane of glass i needed for a window they said No.