is the Hull going to be for a plug... or will you be using this Hull..?
if you are going to use this Hull for the Model then yes by all means cut the openings out before the resin.
if being used for a plug then they need to be made visible by showing the cut lines, this can be done with mico rods
most of the Bigger boats over here that need ballast, they use, used fish tins and fill them with molten lead.
not to sure on the last photo... but I guess it needs to match the plans in some way..
doing fine Paul, keep it up