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In peaches, this indicates a nitrogen deficiency. Have the soil tested to better indicate how much of a deficiency and add a nitrogen heavy fertilizer to the soil.

It sounds as though the tree may have peach canker (which can affect any stone fruit tree). This needs to be addressed, but should not need any chemicals to address it. This article will help:
https://extension.psu.edu/plants/gardening/fphg/stone/diseases/cytospora-canker-of-stone-fruits

This is caused by peach borer, which can affect any stone fruit. This article will help:
https://www.gardeningknowhow.com/edible/fruits/peach/peach-tree-borer.htm

It is hard to say it is will make fruit. Some rootstocks are varieties that fruit and, as you mentioned, will have inferior fruit and others will not fruit at all. Which it will be is impossible to say as different nurseries use different varieties for rootstocks and it is a toss up which the nursery that grew your tree would have used.

Premature fruit drop is normally the result of poor pollination or an insect problem. Overbearing is another possibility. When the fruit is pea size, begin thinning to prevent fruit drop. This will reduce the energy of the tree so it can put more into the production of fruit. If pollination/fertilization is at too great a level for the tree to sustain, all of the set fruit will simply drop. You can also thin the blossoms rather than the fruit.

Without a description of how long it took between the branch looking stressed and the actual branch death, whether or not the leaves are wilted or brown, whether or not the twigs break with a sharp snap or merely bend, is there life in the cambium layer when the bark is scratched, what size is the branch, how old is the tree, has it had an injury, has the tree been stressed...need more information.