[Zu Ra]

if isshin was using his gigai this whole time, how can he make sweet love with ichigo's mom and have 3 kids?

It would be better if kubo could go more in details about all Gigai functions . Too bad he left Gigai and sweet love out -__- . Birds n Bees

Spoiler:

do we ACTUALLY know how a gigai functions?

There are three known types of Gigai in use , Isshin uses the normal Gigai not the combat ready Gigai Urahara uses

Spoiler:

hense Ichigo's weird powers & being a Vaizard.

Ichigo became a Vizard by a Freak Accident it has nothing to do with this i.e Ichi was not smart enough to find the red leatus shinigami threads fast enough.

The Leatsu is indeed questionable . IMHO but that has more to do with SS King theory . URL :SS KING