Hi Rob,
I totally agree with your second point, create your own landing page. A large percentage of my personal EliteDownlineBuilder referrals come from the Thank You page for my Beginners' Crypto Course.
Your third point is interesting. I think 100/0 could work well for marketers who are as fully engaged as you are. For large chunks of the year my own campaigns run more passively so I will stick with 80/20 for now.
As for the first point, about the telephone field, I feel that every extra field increases "friction" - note @aslehansen's comment below. Again, it depends what you are after as a marketer. I do not use telephone marketing, but of course, if you do, then adding a telephone field will build in more friction, attract fewer but better targeted referrals. In short, "friction" can serve as a positive component of your opt-in strategy.
All the best,
DH