With RCI you don't convert the points, they are already converted if you own a converted RCI points week. If you have both points units in the same account it will just show you the total points you have for that use year. It doesn't divide them up by what resort they came from. If you have them in two different RCI accounts you would have to transfer one to the other. I believe one points transfer is free per year with a regular RCI points account. I think you may get multiple free transfers with a platinum account.
As to your question about how long rci points last. You have one use year. So if you bought now, you would likely have something like a use year of July 1, 2016-June 30 2017. As long as you use any points during the year, they will automatically be saved through the end of the following use year, which would be July 1, 2017- June 30, 2018. Your 2016 points would expire June 30, 2018 unless you pay to extend those points. Use years can get a little confusing. You can also borrow ahead and use your points the year before you use year. Not applicable when you first buy and your use year stars this year.