Leftover Confit Tomato Oil?

I grow lots of tomatoes in my garden, and when I have too many, I take the cherry tomatoes and confit them. Its pretty low-effort - tomatoes, garlic, shallots, basil and/or thyme covered in olive oil in a big pyrex in a low oven for a couple of hours. I vacuum seal and freeze the result, which acts as a nice reminder in January that summer is still a thing.

My understanding is that the leftover infused oil is super useful, and it does smell amazing. I don't know what to actually do with it, though, and would like to know what others do. I always end up putting it in the fridge or freezer and forgetting about it - I still have some in the freezer from last summer.

Additional questions include: 1) if the oil is fully separated and I strain it with a coffee filter, is it shelf stable? 2) Should I use that infused oil for my next batch of confit tomatoes, or is that overkill? 3) If I use it as the base for my next batch of regular marinara from canned tomatoes, is that a waste or will it actually improve my sauce?