Implying size makes someome stronger.
Not exactly, but it does contribute to its mass and weight. Proportions is one of the defining elements of the bijuu and Susanoo that make them so dangerous and imposing. A simple kunai or impalement from a regular sized blade would be likened to a pinprick for even the regular boss sized summoning. Hell, the Jubi flicked away a fully powered Bijudama from Gyuki. Gamakichi and Gamabunta are both comparatively small to Katsuyu. Their efforts would amount to the same as Kurama and Gyuki's against the Jubi.
The only feats i see in katsuyu is how she makes a perfect summon in terms of medical healing skills. She's a great support for a medic and she acts like a medium and/or amplifier for their medical powers, act as a shield and absorbing great impact and some basic offensive combat (spit acid) but nothing else more.
Until further demonstrations of its power are given, yes. But the main aspect of Katsuyu isn't its offensive capability (although it's definitely capable of handling itself in combat) but its resilience and insusceptibility to damage. All of the techniques in the world are meaningless if you can't effectively incapacitate your opponent using them.
Now go ahead tell me how endurance and size implies someome is more powerfull.
Read my above responces. Mass and size aren't the sole determinants in how capable or powerful a character is, but they do contribute to various physical stats like strength (mass times acceleration equaling force), durability, damage resistance, speed in distance traveled (considering their size), and the scope of attacks (just do a comparison between the Suiton from your frogs and and the ones used by the common sized shinobi who isn't a mutant like Kisame to understand the context here).
Suiton would do little to nothing against Katsuyu since it thrives off water and hydration as a gastropod. In fact, that might only make it stronger. Water elemental techniques are what comprise the majority of their ninjutsu. All they have left canonically is oil and short swords. Bladed weapons and physical attacks in general are useless against a creature like Katsuyu though since it can divide and reassemble itself, if not outright tank the attack given its resistance feats. And it's unknown what effect, if any, oil would have on a slug. Someone would have to explain that.
Katsuyu is primarily defencive and supplementary in nature, but that doesn't detract from the chances of its success in battle.
Good point, but there's no reason to believe that Tsunade's Byakugou would be limited by the techniques of Mito's. Isn't the seal essentially a) a chakra storage unit and b) a tool coded with specific jutsu. Tsunade could have coded a technique that's similar to Hashirama's Sage Mode into her Byakugou seal, but that doesn't mean that Hashirama had a summoning contract with Katsuyu (he could, but I'm not sure).
The Curse Seal was originally mentioned to be just the human body's chakra being forcibly drawn out. Obviously that we learned that this explanation wasn't quite accurate to what the progenitor of the seal stated. In CS state though you were given the capacity to utilise jutsu and abilities that would normally be unusable (flight like in Sasuke's situation or the ability to project chakra in a laser type attack like the one Juugo used against Raikage). In that respect it's similar to the Byakugou. It could be used as supporting evidence to the theory that they both originate or were inspired by a school of senjutsu. Even if the Byakugou doesn't involve natural energy the fundamentals are similar to Katsuyu's abilities.
Though Hashirama's SM had forehead markings, they look very different --Tsunade's and Sakura's are diamond like, while Hashirama's was circles within circles (looked like the Haruno symbol, right?).
Well the Curse Seal looked nothing like DSM yet it was stated to have originated from Ryuchidou. The Byakugou and its relation to SSM could be the same.
Well the Juubi's empty shell was cultivated from Hashirama's dna, so the fact that it's made out of his DNA and that it turned into this tree, makes you wonder, so to speak.
I overlooked that detail. But if Hashirama's SM was indeed Mokuton based then why would his markings not resemble the Jubi's? Why make comparison between him and Tsunade then? You could juxtapose the markings beneath his eyes to the markings on Katsuyu and some very similar qualities would be noticed. Surely that's not a coincidence.
As for SM, yes, I do. I have been out of town for some days and had no computer access and from the phone is hella hard to type, lol.
I plan on writing it a bit later [need to do some house chores atm 
]
Thank you for the account. A few people haven't forgotten that assurance to explain the training process but time is still in abundance with this manga. Good luck with your tasks.
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