I need a bit of help with this tank

#1

I have a couple of questions. I will be starting the armhole/bust. 1st off it says to put the back half of the stitches on a holder. I have 180 stitches. From the start of the round do I count 45 from each the left and the right to put on a holder? If so the working yarn will then be smack in the middle of the front panel. Or do I take 90 stitches off the left side to put on a holder?

I am also confused about the decreases.
RS: s, k, psso (or ssk), k*, k2tog, Do I only do s,k,psso for the first 2 stitches then knit all the way across until I reach the last 2 stitches, then knit 2 together?

So confusing to me. If it wasn’t for this site I don’t think I would have continued knitting!

#2

If you look under Cast On in the directions, it tells you to mark the beginning of round and the 90th st because this will help you when it comes time to work the front and back. So starting at the marker for beginning of round, slip 90sts to a holder.
And yes, you’re right about the decreases, ssk, knit across to the last 2sts, k2tog. I’m glad you’ve gotten so far along on this tank and look forward to seeing the completed project.