I'd guess that SKP is slip1, knit1, PSSO aswell (i've seen it as SKPO when shortened before so i'd go with it)
The next bit:
The 9 stitches which you either knit or purl are the centre 9, then SKP bit or the P2tog bit picks up the first stitch on the remaining stitches, this forms the heel to turn as you knit it, if you just follow the pattern making sure you turn when it says you shouldn't go far wrong, i make baby bootees which do a similar thing along the top.
I hope this makes sense, if not just shout and i'll try again
Edited to add:
I've done a chart in Excel, hope this can show you what I was trying to explain above







