The Tropical Fruit Forum

I think it also has fertilizer issues.  Organic fertilizers do not work well in container grown trees, as there is not enough micro organisms to brake  down organic fertilizers into a usable forum.  Also, using an excellent fertilizer like Jacks once (a month ago) is also not a proper fertilizer schedule.

Yes, the higher up on the tree the twig will have a higher node count to start it out.

Yes you can repot when fruit are present.

Clearly looks  like it just comes from the rootstock.

 Minneola flowers are self incompatible, thus require pollination by another citrus variety.  Dancy, kinnow and clementine are all good pollinators.

That is a great place to have the Expo.  Thanks Hershell

Magnesium.  Do not apply at high temperatures or low humidity.  Apply in the morning or late afternoon.  Use 4-oz. per gallon warm water as a foliar spray.

 jbtx1234 thanks for your above post on Kroger's less than quality fruit.  The flavorless Sumo fruit in my above post was purchased from Kroger.
                   

My wife purchased 4 Sumo from the store.  They were nether sweet nor sour, just flavorless.

To encourage new branches to grow on a citrus tree after pruning, focus on cutting just above a healthy bud on the branch, which will naturally stimulate new growth from that bud; additionally, you can use a technique called "notching" where you make a small cut in the bark just above the bud to further promote branching; ensure you prune at the right time of year, typically during the dormant season, and provide proper care like adequate sunlight and fertilization to support new growth.

Taken from the Internet

I m growing a white Marsh grapefruit, and also a red grapefruit in zone 5 Colorado inside a greenhouse.   Both do well, however the red fruited grapefruit never turns red. This is due not enough heat.   I  could turn up the greenhouse heat greenhouse but cost would greatly go up.

https://edis.ifas.ufl.edu/publication/HS1425