The garage rocker would work well for you and should save a bit of money.
Please go try on boots before you buy them, good fitting boots are key to having fun on a snowboard, possible the most important thing.
Large footprint isn't really a bad thing but it isn't great either, modern boot design shrinks the footprint of the boots making the toe and heel overhang less, this only effects you when doing deep carves which you probably wont be doing indoors or as a new rider.
No issue with the bindings
Dude, suckin at somethin' is just the first step to bein' sorta good at somethin'