Gundogan is indeed the pick, he's a world class CM which we got for a steal. The comment about fitness holds true with any player and, as has been discussed before, there is no additional reason for concern with Gundogan in this regard.
The assumption Vinny will be out injured isn't unreasonable, but it's clear that he's, pardon the pun, on his last legs on this issue. Stay fit and the place is his, fail in this regard and Pep will move him on. A lack of leadership only exists because players like Otamendi failed to turn up last season, but I'm confident Pep won't allow a similar situation to develop due to a shift in focus.
The midfield being fairly lightweight isn't a valid argument. You know who else has a lightweight midfield? Barcelona. See also, Real Madrid, Bayern Munich and other world class teams. Fernandinho alone is more than enough here in that regard, but Pep's game doesn't necessitate physicality in the middle of the park.
We only need one top quality striker and many would argue that at this point Kelechi is more than promise and has proven he can deliver at the highest level. If we haven't got full confidence in Kun, and we should, then there's no reason Iheanacho can't provide a suitable backup with the firepower that exists elsewhere in the squad also.
Using examples of games last season isn't indicative of how things will play out under Pep.
The transfer window is only open 13 days, nobody is suggesting we are finished, not by a long shot, but to suggest the signings we have made already, all of whom have been handpicked by Pep, are disappointing is ridiculous and frankly naive in the extreme. I'm not suggesting you agree with that, but that was certainly the crux of the argument I responded to.