do you actually have a reason to stay away from halo? I would highly recommend it, and 3 weeks is a great duration. Halo gave me better results than any other oral I"ve ever taken, in the shortest amount of time, as far as strength was concerned. If your only reason is 'liver toxic' or 'cardio health', you should say that, because that's a risk everyone has to consider for themselves. If the dude's potential wilks score is as high as he says it is, he's very very strong and lifting at a high enough level that one would assume he's willing to take risks for his sport.
OP: Now I'll address the wilks thing with you.... You don't have a wilks score until you do it on the platform. Period. You've never done these lifts under competition conditions, so until you do that, your wilks score is 0. This is a general concept that almost all competitive lifters agree on.
Yes, halo can do a lot for you in a short period of time, regardless of what you're taking. I was actually running tren e as well the first time I used it, and it made an ENORMOUS difference. One of the best orals out there.
Adding tren a is not necessary. if you want more tren in your body, you can just up your dose of tren e. i mean, there's no real problem with adding the ace in, but i think you're overthinking that. if i had to choose between adding tren a, and adding halo, i would definitely do the halo.
as to your 3rd question, that's such an individual thing. I don't think halo itself will cause that sort of problem. And whatever other compounds you're running are relevant to this question.