Yes you can apply for a raise in listing limits by saying you have another account, may perhaps cause them to look at this account though so don't know if I would risk that.

If you were sending cancellation requests stating the buyer no longer wanted to buy then you should not be getting defects, are you sure that is what they are for?  I never send cancellation requests unless a close relative can provide a death certificate, if the buyer doesn't want to pay for ANY reason then they get a strike......end of.

I wouldn't stop listing and selling on this id altogether,  perhaps close the store and list a few things every week as auctions or BINS, sell something that is less likely to get cancellation requests, in order to build the feedback up a bit until restrictions have been lifted.