Here is one.

Recipes that call for a # of peppers would be same # thawed or fresh. Since yours are already chopped (not sure why you would chop before freezing?) all I can think of is to get a fresh one, chop it, and measure it for comparison.

is there a formula for x pounds of low acid ingredients need x cups of vinegar to acidify safely for jam?

No. Each has to be tested individually.

I used 1 1/3 pounds of peppers would 1 cup of Apple Cider Vinegar and 5 cups of Sugar be safe?

Can't say. It would just be a guess.

Finally, I do not blend my peppers such that there is a variance in how many peppers are in each jar, I try and even it out but sometimes jars get more peppers and sometimes less when I pour in the jam. Could this pose a safety risk?

Not if it is properly acidified when made. The pH level would be uniform.

If I make jam and refrigerate (not process in BWB) is there a general rule for safe refrigerated shelf life (6 weeks? 2 weeks?)

If using a tested and approved recipe then in theory it should be safe from anything but molds. The general guideline is 3-6 weeks but that is open to all sorts of variables. Processing eliminates any concerns.

Dave