Welcome to the forums sixdoubleo. I am not much of a kit maker so I will let someone else answer specifics on that, but it looks likes things are going great with your first kit. Checking your SG is much more important than the days that they tell you that it will take. It sounds like your...
I have made concord grape and a batch of white grape/peach. I used 3cans of frozen concentrate per gallon. I used a starting sg of 1.080 on the concord and 1.070 on the white grape/peach and both turned out pretty tasty.
I agree, the potasium meta in the juice won't stop you from making wine. Just give it the 24 hours before pitching the yeast. I just used the 3can per gallon recipe and it turned out great. I back sweetened with 4 cans of the same juice concentrate.
How big of a chip? I am just wondering how much gas you get with a certain size chip of dry ice? How much space do you need in the carboy for the volcano?