Sl1, after dividing stitches for sock heel

This is my first attempt at making socks.
My sock pattern tells me to divide my stitches, by knitting so many stitches, then putting half of them on a holder.
Then it tells me:
Sl1 then purl across. Turn.
then for the next row
Sl1 K1 across the row to the end. Turn.
My question is, do I need to slip the stitches knitwise on the knit row and purlwise on the purl row? Or do I simply slip the stitches onto the other needle (which would be purlwise)
Also, at the beginning of each row, I am to slip 1. Knitwise? Purlwise? I am unclear. I looked a seeral patterns, and they all just say Sl1.

When a pattern says to slip one, slip purlwise unless the pattern specifies otherwise (often decreases are slipped knitwise). For a sock heel, I slip purlwise on all the heel rows.