Where to start?
1) Tsunade is indeed a Senju as she is the goddaughter of the first. Despite that lineage, Hokage is not a dynastic entity. Perhaps the Feudal Lords are, but Kages are chosen from ALL ninja and it is usually the strongest. Now, it appears that Kages come from families that have strong ninja in general, but it doesn't necessarily happen that way. The first two were Senju clan, then Sarutobi clan produced the third, Minato had no identifiable clan and then it went back to Senju. Kakashi also has not been given to a particular clan and he was nearly hokage - because he was one of the strongest.
2) Naruto has not be identified as Senju - he has no specified clan. Any link between him and the Senju has been hinted at only (and by Madara - if you want to believe a guy who doesn't show his face). There is no evidence that there is any link and if there was, I think Tsunade would have made some reference to it, especially during this conversation about remembering Minato, Kushina and Naruto.
3) It has already be said, but it is worth saying again: the Senju were a massive clan and they brought in a lot of other clans to create Konoha. They didn't all stick to the same clan - that's just genetically unhealthy. Plus, you'd get more diverse and strong nin by interbreeding - which I'm sure was known.
Finally, whether or not you want to reward people for reading between the lines and finding evidence for any type of theory is fine, but don't label it brave or forward thinking. It is still just grasping at minor straws and theories that don't hold up when you think about them and the evidence at hand. The words and panels are all we have and the only proof anyone can use - you can look farther if you want, but don't be surprised with people refute you using the manga as proof.