Am I correct in my understanding that I would not qualify for any of my normal Premier Silver benefits if I book Basic Economy? No free checked bags, Boarding Group 2, seat upgrade, etc.?
Yup. I always book United Basic Economy. If I book through my card I get the 2 free checked bags and boarding group 2. Then from my MilagePlus I have the upgrade to Economy Plus for free and the upgrade to group 1. I'm on flight 12 this year and I haven't had any issues thus far.
From what I understand you do not get segments for Basic Economy.
Another hack is that if you are traveling with kids under 12? on basic economy you can select seats at purchase for no charge to ensure you all sit together. As a family of 5, this saves us a ton of money.