You've got a couple of problems here ....
The traditional way to saute the veal for Veal Marsala would be in either butter (preferably califfied to increase it's smoke point) or a 50/50 mix of butter and olive oil. Since veal has a delicate flavor, yeah, bacon drippin's probably would be a little intense. But, in her defense, I'm sure some "chef" on TV once sauted a little pancheta in some olive oil and said, "If you can't find panchetta you can use bacon."
I think the general "rule" for which stock to use with what would probably be - use a stock from the same critter you're cooking. Beef for beef, chicken for chicken, etc. are fairly obvious. For veal, if you don't have veal stock, you could substitute 1/2 beef and 1/2 chicken stock - comes out close, or 1/3 beef, 1/3 chicken, 1/3 vegetable.
For seafood - best to stick with a "seafood" stock. These are so quick and easy compared with anything else. For fish stock, heads and bones - for lobster or shrimp the shells - crab really needs shells and meat. Just put them in a pot of cold water, bring to a boil, reduce the heat to a simmer for about 30 minutes. A substitute would be bottled clam juice.
For pork stock - it depends on the flavor you're after - fat back, salt pork (blanched first to get rid of some of the salt), ham hocks, or a ham bone.
Of course - you can "thin out" the intensity of any stock by adding water, or vegetable broth.
I'm not a big fan of using bullion cubes in place of stock/broth because of the salt - but Knorr makes some pretty good ones - especially good for a quick fish broth.
Bacon isn't a stock - it's a fat. It depends on how you use it, and the flavor you want to achive, as to whether it is the appropriate fat to use or not. I can think of LOTS of recipes that use bacon ... with beef, chicken, and shellfish.