So, here's something along the lines of what I'm trying to do:

for every row where column x says "foo" countif(y:y,"<100")

maybe it's something like countif(and(x:x="foo",y:y<100))
or maybe it's a whole other function.

I keep having to create extra go-between columns that concatenate two
columns, and then work from that:

x1&if(y1<100,"Yes","No")

drag it all the way down the side of my data

and then do something like:

countif(z:z,"fooYes")

It's a pain in the arse, I tell you whot. Please help me out.