Why is ground beef red on the bottom also

(1) Yes, that's fine. If you use freezer bags, you don't need foil even. For longer-term frozen storage, vacuum sealed bags work better.

(2) Frozen food stored at 0°F (or lower) is basically safe to eat forever. Eventually, the flavor will be affected and you won't want to eat it (but it won't make you sick). Three to four months is reasonable in tightly-sealed freezer bags. Longer in vacuum sealed bags. The storage time is entirely a flavor thing, so you can get away with a little longer for strongly-seasoned meat (e.g., tacos) vs. lightly seasoned (hamburger). The sell-by date assumes storage at around 30°F (normal for refrigerated meat)

(3) I believe so, stuff should still be good a few days after the sell by date.

Per the FDA, you can hold the ground beef, refrigerated, for one to two days.

Assuming you have:

• Bought the meat from a reputable source (you seem to have if you watched them wrap it)
• Have kept it well refrigerated since buying it, and will do so until cooking it

I would just cook and eat it as normal at dinner time tomorrow, since it has been refrigerated the entire time. 24 hours is not a magic number. 26 or 28 hours is not that different.

Now, several days extra time before cooking would be a big difference compared to several hours.