Ummm, my brain is a little fried from teaching teenagers trigonometry all day, but, I think the interpretation is;
You should have a centerpoint from nock to middle of the handle to nock. I'll use a string with a couple fishing weights on each end to line them up and make sure the bow is straight.
The bow's width will reduce at mid-limb, say 1.75 inches?, down to 3/8 at nocks. In other words, at mid-limb, you'd have 7/8 inch to one side of center and 7/8 inch to the other, reducing it's width to 3/16 at one side of nock on left and right of center.
Let me recommend making your bow cuts a bit wider and working down. When I make mine, I start my nocks at 1/2 inch at first then reduce width when the bow is almost complete and I'm down to final tillering.
Don't underestimate your Stanley Surform rasp. It sounds like I have the same one. I'll use it during floor tillering to get the limbs bending, but don't rush it. You can't put the wood back on. When I first started, I wasn't using the rasp properly, I was pushing it 'straight on' with the bow limb, not angling the tool to get the teeth orientated with the limb. Stop using the surform rasp at floor tillering and switch to a scraper from then on.
"Do this on all 4 limbs", I think it does mean, do this on all four sides.
I started a year and half ago, and haven't stopped. Wait until you lay in bed at night thinking about new bow possibilities, that's when it's time to admit you have a problem. Don't worry, we're all here to sympathize!
Best of luck to you.
Parnell