Partial answer

F E OZ OO ON TZ TS FF FS

This refers to the first letters of digits. Z=0, O=1, etc.
F, T and S are ambiguous though, which is where the numbers in the messages come in.

The first message:

you must not go out at two, five, or seven. This implies for the first message, T=3, F=4, S=6. So we have:
4 8 10 11 19 30 36 44 46

The second message:

Avoid your fellow brothers until then at three, five, and six. This implies for the second message, T=2, F=4, S=7. So we have:
4 8 10 11 19 20 27 44 47

Start at decryption:

The presence of the acronym in the second message suggests that the first letters of words might be important. The numbers above could refer to word indices. In the first message, this gives "wctatsgrm", in the second, "fzssooonz". The second is more interesting because it itself follows the same digit-letter mapping.

The target is:

Vivint Smart Home Arena (where the Utah Jazz play), with the recon zone being the college to the north.

F E OZ OO ON TZ TS FF FS

This refers to the first letters of digits. Z=0, O=1, etc.
F, T and S are ambiguous though, which is where the numbers in the messages come in.

The first message:

you must not go out at two, five, or seven. This implies for the first message, T=3, F=4, S=6. So we have:
4 8 10 11 19 30 36 44 46

The second message:

Avoid your fellow brothers until then at three, five, and six. This implies for the second message, T=2, F=4, S=7. So we have:
4 8 10 11 19 20 27 44 47

Decryption:

The presence of the acronym in the second message suggests that the first letters of words might be important. The numbers above refer to word indices. In the first message, this gives "wctatsgrm", in the second, "fzssooonz". The second is more interesting because it itself follows the same digit-letter mapping. Decoding with the second set of numbers (2-4-7), we get 407711190.

Location:

Now that we have the numbers, we can treat them as coordinates, as contributed by @Sleafar.

40.77, 111.90

It could be that "it's negative only on a flare signal you would see overhead" should be taken as a hint that one of the coordinates is negative. Either way only 40.77, -111.90 lies in the U.S. as we know the objective to be.

Looking at Google Maps, this is in Salt Lake City, in a building of LDS Business College. As we have the phrase "the school sits just north of the objective", this implies that the Arena to the south is the target, and the school is the recon zone.

I'm still curious as to what the first message, including the numbers on the hand, was meant to convey; that is not part of this answer.