I have just made several pounds of Scarpetta's tomato sauce. Can I freeze the leftovers in strong plastic bags and just break off some for future use?

How about freezing small amounts in muffin pans, then once frozen, tipping into a ziplock bag for longer-term storage?

Don't know what your experience may be in this sort of thing, but breaking some off may not be so very easy, and hard to be accurate with.. Of course there are alternatives- if your portion sizes are not predictable enough to package it that way, you can always partially thaw (a microwave is good for this) or saw it off- my mother always kept a hacksaw in the kitchen for this purpose, though usually for meat. I must say it produced some peculiar saw dust.

Yes, you can. It's a great idea, in fact.

I freeze sauce (and leftovers) in serving size portions. Some are a single serving, others for a full family dinner.

I freeze my recipe in 1 or 2 cup portions in 1 quart freezer bags. For me it’s more manageble that way.