Is it ok to start off your seedling in a 1-2 gallon size pot of coco/perlite mix right from the start?
Sure, that's how it happens in nature. Make sure the mix retains enough water to get it going, and watch it closely; you don't want to let it dry out in the early stages.
Yes it's fine but remember that even though you water the whole pot the roots haven't reached there yet so try to remember to water the root ball and gradually water more as the plant gets bigger