By choku tomoe he was referring to EMS which only grants a power boost of feats the user had with MS, Hashirama didn't have anything extra, he had Ashura's powers it's simple as that, the ability to absorb NE and use Mokuton comes from someone that had Hagoromo's body.
No he wasn't. The Choku Tomoe was considered to be an ability that extends beyond the Uchiha bloodline (Transmigration) whereas that was not the case with the EMS.
Ashura never possessed Mokuton meaning that this wasn't an ability that is part of the Senju bloodline, so Hashirama did possess something extra.
Ashura's avatar wouldn't be possible without bijuu chakra and since he wasn't a Jinchuuriki that suggests he inherited some of the Juubi's chakra.
Ashura's Avatar is just a manifestation of Ashura's own Chakra and we have to take into account how he had Rikudou Senjutsu which isn't something he inherited, so RSM could've been the main reason he could use a Chakra Construct.
Him and Indra were both conceived when Hagoromo was the Juubi's host, which means whatever power they inherited from the Sage had some of the Juubi's influence. The Sharingan comes from the Juubi's eye while the ability to use RSM and TSB comes from the JuubiJin's body.
Sharingan isn't the Juubi's Eyes. The Juubi's Eyes is composed of both the Sharingan and Rinnegan's powers to its full extent. Indra only inherited a devolved form of that due to only inheriting Rikudou's Yin Chakra. Likewise, RSM doesn't just come from having Rikudou's Yang Chakra, but rather, his complete chakra along with Senjutsu as that's considered a Six Paths Power, not Ashura's Power.
Yes but notice that EMS Sasuke never showed the mastery over Susano'o like Madara until he had Sage chakra, he was only capable of channeling ninjutsu through the avatar but it wasn't until he had the Rinnegan that he displayed the raw power Madara's Susano'o had.
This is because his chakra potency wasn't on par with Madara's, but this is irrelevant when Orochimaru confirmed that EMS Sasuke had the potential to surpass EMS Madara.
Rikudou Chakra simply provided him with greater Chakra Volume and Potency which can also be obtained through training.
Before that his avatar was the same size as Naruto's BM which was about 1/3 the size of original Kurama who Madara was able to wrap Susano'o around effortlessly, this suggests that Madara's PS was unique to him just as Enton weapons are unique to Sasuke.
The reason for that was due to his Chakra Volume, Potency, and lack of Experience. Let him develop all three of these aspects and he would've reached a level above Madara as stated in the manga.