a)
In my experience EQ + low test is a mess. It seems that EQ crashes E2 i don't know but i end up with superlow e2.
low test + everything else works, but it's another ballgame, and if you workout low volume high intensity doesn't work good.
In the end Arnold used Dbol + Primo in hefty doses and got "big", for his era, but he was an high volume guy.
b)
low Test = low EQ i.e. 250 Test 250 EQ works fine, adds a bit of fullness
c)
You can go NO TEST and use EQ as your estrogenic base, IF you need to raise RBC, Hemoglobin etc, it's a "choice" but imho it's something more for sport and performance than bodybuilding.
I did it and works, felt good, had less water than on 250 TestE, same sexdrive, but you have to use min. 500-600 EQ or you won't make enough E2 to function. (that maybe in this case will be E1), overall i think that this approach isn't best for bodybuilding but some guys from Arab countries used that approach in the past.
For bodybuilding usually people goes for high test low-medium anabolics (go into Luki's thread/posts and get inspired) paired with low volume high intensity workout, i am not saying it's the best, but if you look at new pros most of them (Hunter Labrada, Nick Walker, Chris Bumstead, etc) use that approach.
IMHO there's a correlation between which anabolic protocol you use and workout, but it's OT.