2) I’m having trouble with instructions that mix the symbols * * and [ ] in the same line.

Row 6: K1, K1B, P1, K1B, K7 *K1B [ P1, K1B ] 4 TIMES; K7; REPEAT FROM * TO LAST 4 STS. K1B, P1, K1B,K1

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KT has already given an excellent and accurate interpretation of the symbols, and an explanation of how to work K1B. I just wanted to add that it may help you to write out the instructions, either on separate lines or with each grouping separate, like this:

K1, K1B, P1, K1B, K7
* (I indent this grouping to make it easier to recognize it)
... K1B
... [P1, K1B] (the [ ] indicate a grouping within the larger * grouping)
... [P1, K1B]
... [P1, K1B]
... [P1, K1B]
... K7
repeat from * to last 4 sts (This is where the * grouping ends)
K1B, P1, K1B, K1

BTW, note that the * grouping could also have been written
*
... [K1B, P1]
... [K1B, P1]
... [K1B, P1]
... [K1B, P1]
... K1B
... K7
repeat from * to last 4 sts

because you are alternating K1B and P1 on an odd number of stitches, so either the beginning or ending K1B will be outside the [ ] pairs. Either way, I think the [ ] make it easier to see/understand and keep track of what you are working, rather than

... K1B, P1, K1B, P1, K1B, P1, K1B, P1, K1B

I would lose my place in that line and would end up counting K1Bs or P1s anyhow.

All this is knitting shorthand, of course (imagine how long it would be to write all that out completely), but you will get better at deciphering all those symbols, groupings and repeats as you gain experience. And we are always here to help you learn so if you get stuck, please post again.