If you wanted pot roast, you should have made it pot roast from the giddyup, yes.
I didn't suggest you should poele. I was talking about options. If you tell me what you want to do, I might be able to tell you how to do it -- from one of a number of perspectives -- home cook, "American Bistro," small catering, 'q, French, and "California Cuisine," to name several. Chef Ed and I have some overlap, but he knows a lot more than I do about serving big numbers. Other people here bring different perspectives.
I'm not really familiar with pressure-cooking. I know great things can be done, but I've never tried to do them.
Before I comment on this, I'd like to know what you mean by jus, what the sequences were, and some rough idea of quantities.
One of the problems we're having is the meaning of the term "roast beef." I see Chef Ed is trying to get some clarity on this, too.
When you say "roast beef," do you mean roasted uncovered like a rib roast? roasted covered like a poele; or braised like a pot roast?
Not necessaily. You've pre-sliced and packed in sauce. As long as the reheating process is relatively gentle, and the packets are not too thick, reheating from frozen shouldn't be a problem in microwave or in vacuum packs reheated in hot water.
Not much of an issue. All fond is good fond -- at least as long as it isn't carbonized.
Now that IS a problem.
Aha! I see. If you care (and you shouldn't), the proper name for it is a "stock-enriched jus lie."
Bottom line: If I had a better idea of what you're trying to do, in terms of the exact nature of the dish, the number of servings, the nature of the setting (retirement home, country-club, work-site, ...?), and so on, I can either do a better job of helping or letting you know you're outside my limited area of competence.