Sweet Baby Cap, but i need help please

I am a beginner - intermediate knitter.

Here is a link to a very sweet hat pattern that i want to try out.

I have cast on 121 st, and i’ve knitted the 7 rounds, and i am about to start the increases/decreases to form the cute bits of the hat, however, i am confused already.

k1, M1, k18 (18) 19, slip 1 - knit 2 tog tbl - psso, k 18 (19) 20, M1, k1, M1 k 18 (19) 20, slip 1 - knit 2 tog tbl - psso, k 18 (19) 20, M1, k1, M1, k 18 (19) 20, slip 1 - knit 2 tog tbl - psso, k 18 (18) 19, M1, k1

Can anyone help me with the following.
a) M1, can i knit into the front and the back of the same stitch and this would take care of the very first k1, m1? or should i follow instructions for M1f?
b) tbl, i looked in the glossary here and it says ‘through the back loop’ what exactly do i do here?
c) pass the slipped stitch over, again i looked in the glossary here and it says ‘pass the slipped stitch over’, what does that mean? do i slip one stitch, knit the next stitch and then pass that slipped stitch back over the knitted one as if i was casting off?

many many thanks in advance.
Charlie x

Here is the main part of the pattern below, for ease.

Gauge: 28 stitches = 10 cm

Yarn: 50 grams of light and dark pink yarn, baby weight.

Sizes: 6 mo (1) 2 yr

CO 121 (125) 131 stitches with 2.5 mm circular needle, join then knit 7 rounds in garter stitch (purl one round, then knit one round) then change to 3 mm needles and knit in stockinette stitch, changing colors every 2 rows.

On the next round, increase and decrease as follows:
k1, M1, k18 (18) 19, slip 1 - knit 2 tog tbl - psso, k 18 (19) 20, M1, k1, M1 k 18 (19) 20, slip 1 - knit 2 tog tbl - psso, k 18 (19) 20, M1, k1, M1, k 18 (19) 20, slip 1 - knit 2 tog tbl - psso, k 18 (18) 19, M1, k1

Repeat these increases and decreases every other round for 8 (9) 10 more rounds. Then do only the decreases every other round until there are 7 (11) 11 stitches left. Then k2tog until only one stitch is left, break yarn and thread through remaining stitches.

Steam block the cap from the inside with a damp cloth over. Attach crocheted or I-cord ribbon in each side.

a) generally the M1 front, or you can kfb in the first k1

b) a stitch has 2 legs, one in front of the needle, one in back of the needle and we normally knit into the front one. Knit into the back one this time. There’s video for this on the Glossary page.

c) On a decrease of slip 1, knit 1, psso, you take the slipped stitch over the k 1 st, a little like you pass the stitch over the other in a BO. There’s a video for it on the Glossary page under sl 1, k1, psso / skp