What are the customs at a wedding regarding how to divide which side gets what with tenaim/kesubah/kiddushin etc.
The custom nowadays by many is that the eidim (witnesses) of the various things gets divided between the two sides. It doesn’t have to always be this way, and there is nothing essentially wrong with one side getting more than the other side.
Regarding the kibbudim at the chuppah itself, generally the chosen’s side chooses the mesader kedushin, who will often be the Rosh Yeshiva of the chosson, then the Kriyas Kesubah Honor is given to the kallah’s side. The last bracha (the third biggest “kibbud”) goes to the choson’s side, and the first two brachos to the kallah. The other brachos get split evenly.
Often there can be friction between the two sides over different issues regarding the chasunah. One such issue is how the choson and kallah should be led to the chuppah. Some want it that the parents of each side walk their child down, others want that the two fathers walk the choson and the two mothers walk the kallah. There is a famous story about two sides that came to R’ Y. Kaminetsky to ask him what they should do, and what the correct minhag is. R’ Yackov answered them “Our minhag is to make the other side happy. We have 8 children, four we walk down this way and four we walk down the other way!” This is the general rule and the correct minhag.