you can walk over to a resort that their bus goes too. Of course then you would have to figure out the times and everything.
the taxi should be less than $20.
yes they have plus size clothes. now the Disney outlet there might or might not. Sometimes they do have plus size other times they don't. that place is hard to predict.
also look at the gift shops at your resort. Sometimes they are having an unadvertised sale. this is not the time to be shy. You need to ask someone if they are having a sale and if so, where is it.
my best deal was on Disney property at the Polyn. a swimming suite that I wish still had - actually made me look thinner!!!! it was $125 - mark down $75, then mark down to $35 - what made it a great deal - was about 6 months later found the same swimming suite here for the $125....