Re: Tools needed for a beginner to cut glass to cover a dining table?
If the glass is tempered (heat treated) it will shatter when you attempt to cut it. You may also find it difficult to even get the scoreline to run. If, as you say, the glass is from a commercial setting it most likely is tempered.
A glass supplier could tell you if it's tempered if there's no acid-etched label on the pieces. Older glass may not have that as it wasn't always law.
Put 'Tempered glass identification' into Google. Lots of hits come up.