I appreciate your eagerness to keep your doses lower. It's a good policy.
As far as test:nandrolone ratio, it's honestly a purely subjective thing. Some guys like a 2:1, some like 1:1, some like more nandrolone. Me personally with test and npp, I like a 1:1. But that said, I always run it with an equal amount of mast too. Seems to keep the water retention down a little and mast just always makes me feel better overall.
I like NPP over deca for shorter blasts. Deca just takes too long to start seeing results, NPP is quick. NPP also seems to hold a little less water,but water retention is mostly diet. Longer runs I prefer deca because I'm work out on pinning frequently.
I prefer aromasin for my AI. Adex seems to cause e2 rebound when I miss doses, which I'm bad about with that. However, if the aromasin isn't enough or I have to run way too much, I'll switch to adex.
ED can always happen with any gear, but especially nandrolone. For me I don't really get ED, I just can't hardly get off. It's fucking annoying because I only have so much cardio to give before I'm done lol. That's where the mast comes in and really helps for me big time. I still take longer to get off but it's not nearly as bad as it is without the mast.
Also as started above, I run 50mg P5P before bed with nandrolone. Helps keep the gyno from popping up. These days I have to use nolva on anything above 150mg of test even with the AI because my gyno is getting super sensitive. Good to have plenty of nolva and some caber on hand in case you need it. I always have a large stash of both just in case.