1 - Yes you can choose to stop your adventure and go back to shore after you have completed the current card's effects.
2 - If you had to somehow end your temple exploration incomplete, just leave the incomplete cards in the Pending explorations area. At that point you can choose to reengage the Temple or just explore as normal. You can just choose not to go back in it, but then you also risk a Pending explorations area taken up. (not that bad of a risk really...)
3 - I just leave it partially explored and do not reshuffle the temple cards back in. If you complete a Labyrinthic Corridor successfully you weren't really lost - I figure the explorers were somehow able to mark their way deeper into the temple and could use those marks to get back.
Ok, that's what I was half thinking and such, especially since you could rack up some serious VPs in there, just diving in every time assuming we survive could net a killer win.
I guess #1 was worded poorly, I was curious on if you could finish let's say 3 temple cards, then try to head back to shore?