Refinance has nothing to do with potential taxes when you sell, or property taxes.
The taxes when you sell will be based on the cost basis, which is the purchase price, plus any improvments you may have made (such as adding a bath or major remodels, etc, but not maintenance).
Cost basis is:
Purchase price
+ Purchase costs (title & escrow fees, real estate agent commissions, etc.)
+ Improvements (replacing the roof, new furnace, etc.)
+ Selling costs (title & escrow fees, real estate agent commissions, etc.)
If you convert it to a rental property, you would also have to account for depreciation.
