From your posts in both threads, you have either broken a total of 5 or 7 spokes. With that many spokes broken, the remaining have fatigue issues.
I would either have the wheel rebuilt by a competent wheel builder or replace the rear wheel with a mountain bike wheel. The cost of spokes, nipples and a round trip via UPS or US Mail to NJ to Noglider is likely your cheapest option.
Competent wheel builders are a very rare breed, but I'd bet there is a good one on your island. Find the local bicycle club and ask around.
You should have a 36 hole hub which is plenty strong.
As for tires, try these
http://www.schwalbetires.com/node/1328 (Schwalbe Big Apples), I love them. They have a supple side wall and do not eat up the amount of energy that their size suggests they might.
If money is an issue, buy a spoke wrench, spokes, nipples, go to youtube and lookup expertvillage and bike wheel building. Also read this:
http://www.sheldonbrown.com/wheelbuild.html