Taxes and Condoizing a 2 family house

I have owned a 2 family house for 25 years. I have lived in one unit and rented the other. I am considering condoizing and selling my unit and moving int the rental until. I plan to stay at least 2.5 years and then sell that unit.

When I condoize do i have recapture all the depreciation in that year or can I wait until I sell that unit. When I sell that unit after 2.5 years, can I get a full $500,000 capital gains exclusion or will I be able to exclude just the percentage of time I have used it as a primary residence as a percentage of the whole time I have owned it. ex - 2.5/27.5 Any clarification would be greatly appreciated. Thank you