Something to keep in mind is that he would have both elemental affinity for earth and water and also an affinity for yang to make the wood element and not only that, he could have the wood element but what he doesn't have is the large chakra reserves of Hashirama Senju, his wood element would be weak at the level of Tenzo who is a ninja who has the wood element but is much weaker than Hashirama's.
If he has a regenerative factor he could do harder workouts than Midoriya since his body will adapt faster to those workouts so you could do workouts where he breaks down both bones and muscle fibers to make them stronger and more durable.
One thing to keep in mind is that the other nations do not have knowledge of the shadow clone jutsu so they could create clones but they would be more occasional ones and not those from Konoha.
I think he would have more chakra than a common ninja thanks to his Senju lineage and not only that but also since he is a reincarnation his yin chakra will be more than the common spiritually.
Something I realize is that thanks to the passive sage mode that he has is that he can do stronger weight training since the sage mode gives an increased healing factor to its wearer and not only that but it could also function as a chakra boost when his normal chakra is recomposed and also the elemental jutsu are enhanced by natural energy.
better to kill them and since they will be very annoying in the future and will be very serious threats in itself, you already gave them the opportunity to live and they wasted it, so better dead than alive.
*Senjus
you know that the disappearance of feelings was not boiling's fault but rather hashirama's since he made a good part of them marry civilians and their blood became weaker and not only that but also possibly the others were killed by madara in secrets and other ninja villages.
If you unlock the touki, a change that the protagonist could have could be an increase in magical potential because those two are a bit almost the same except that one is to enhance physical abilities and the other is long-range, that means that their magical reserves.
Mushoku Tensei: Reincarnated as the weakest Sword God
Anime & Comics · Brian17Greyrath