Will this turn out well if I reheat it on the stovetop? Imy oven will need to be at 375 for something else during at the same time that I need to...

Preparing brisket a day ahead is a good idea -- flavors will blend and improve, and after refrigerating, fat is easy to remove. Preparing ahead and reheating is actually advantageous. Reheating on stovetop is fine (as per previous comments).

When reheating a braise, the key is to keep the heat low (i.e. braising temperature, sub-simmer) and the time short so as not to remelt the gelatin. I don't believe the pot or pan will make much if any difference except that it be covered (foil is okay) and avoid glass on the cooktop.

Yes, you can place it in a heavy pot, preferably a Dutch oven, and cook it on stove top on low heat. Make sure the meat is covered by the liquid. You can also place it in a slow cooker if you have one.