Yes-- what we were working on was the knit-side increase. Also remember that if you using circulars and are increasing in the midst of ribbing, but are going to be changing to stockinette stitch in the next row, that even in the purl parts of the rib that you want to use the knit-side increase, because you are going to be knitting from here on out and it will blend in just fine. The goal in increasing stitches is to do it as unobstrusively as possible, unless it's part of the pattern to make them stand out.
If I were using your pattern and it told me to increase from 84 to 96 stitches, here is what I would do: I would subtract 84 from 96 to find out how many stitches I had to add, and the answer would be 12. Then I would divide 84 by 12 and come up with 7, and so I would make an increase after every 7 stitches. Because 7 is an odd number and most ribbing patterns occur in an even number of stitches, some increases would fall in the knitting part of the ribbing, and some would fall in the purl part of the ribbing. But as I said above, if you're about to switch to stockinette stitch, that's just fine! And if not, then I would put an increase in after 6 stitches, and then 8 and then 6, and then 8, etc., so that it would come out at the end. What I do, is about 10 - 20 stitches from the end of the round, I count to see if I'm okay on my increases and then if I've done too many, I just don't do any more, or if I've forgotten 1 or 2 somewhere, I just work them in evenly in the stitches I've got remaining.
Now, would you ever do all purling? Not commonly. If you are knitting in the round and doing stockinette stitch, you knit every row. If you are knitting flat, with straight needles, and are doing stockinette stitch, you knit one row, purl one row. If you are working flat OR in the round and doing garter stitch, you knit every row. Sometimes, there will be a pattern where you want the purling outside. I personally think that that is, well, fairly ugly:). So I don't ever do patterns like that. But if you were doing that and working in the round, then yes, you would purl every row. Other than that, you will have little need to increase on the purl side, and even if you do, you can either work around it, or (and I love this idea!--) wait until you are more experienced and comfortable.
So 2 questions: What is it that you are working on right now, and what have you made in the past? Oh, and a 3rd-- how long have you been knitting? Oops, and 4th:-)-- did you ever figure out how to get from one size circular to another?