#1
I find it difficult to know exactly where in the song I am while playing this. There are a few long/drawn out riffs in the song, mainly the first riff and the middle section when jimmy page uses the violin bow. Basically what I have done for the section with the bow "solo" is divide it into three parts. I count 1 ee and ah 2 ee and ah 3 ee and ah etc. up to 8 ee and ah for the first part. Then I count 1 ee and ah through 8 ee and ah 3 times for the middle part. Then the last part I count 1 ee and ah through 8 ee and ah once, 1 ee and ah through 4 ee and ah once, and then five more beats. Please just tell me I'm stupid and that there's an easier way to go about this
#2
How long have you played? When you play a lot you just get a feel for how long it's been. I won't lie though, if I was playing something live that had like 8 bars of the same thing with no variation... if I even slightly drifted off I'd be screwed.

Some people go

1e+a 2e+a 3e+a 4e+a, then they name the beat at the beginning and would continue saying:
2e+a, 2e+a, 3e+a, 4e+a, ... 3e+a, 2e+a, 3e+a, 4e+a, ... 4e+a, 2e+a, 3e+a, 4e+a, ... 5e+a, 2e+a, 3e+a, 4e+a

Basically making the first integer what the name of the bar they're on. Hope that helps.