Guild( pantheon) isn't beneath the tower , is probably on the north -west main Street also known as adventure road. There is only exchange and few facilities like shower, hospital for adventure beneath the tower.

He can make nano tech iron man suit or can use nano tech to disguise his watch by using upgrade.

Don't use any stupid items from other anime it will just ruined the story.

Putting the limitation is a bad move , now he is just a slave of the system.

Little rex ,seriously, is he a idiot , why would someone want to be called little.

He forgot to collect crystals

He could have learn rasengan an a rank jutsu by himself there no need for scroll and become a chunin.

Is he stupid enough that he can't even think this simple regimen for himself, I guess side-effects of having too much intelligence. What kind of books he read in library that system need to scan ?

That just a forced nerfing.. Even yang Kai was stronger than him . He has completely forgotten about using demonic eyes uses like absorbing souls anyone that died nearby and soul attack

He wanted to be human then suddenly order demons to massacre humans instead of killing demons . At least he could tried to stop them from killing humans.

Author has completely forgotten about the development skill.

Mikoto was level 2 around this arc. She and bell were given the name at the same time.