I have a 2005 MCS convertible, wanted to know if there's a spray or sealant, maintenance that I should do for the roof? Also, have a small leak on the passenger side right at the joint where the convertible will fold, near the end of the passenger's top back end, wonder if a scotch guard spray might help push water away from the edges. Thanks!

 

http://www.303products.com/

or

http://www.wolfsteins.com/index2.php

No other products need apply.

 

The two most commonly recommended products for convertible tops are 303 and RaggTopp.

I use 303 and it works well:
I've noticed that 303 is often recommended in boating and sailing, which is a testament to its effectiveness.

As for your leak, I don't think a fabric protectant will be sufficient and you should probably patch it in some way (sorry but I don't have a recommendation how). There are some spots in the original 2005 convertible top that chafe when the top is down. MINI improved it in later years and actually had to replace some tops under warranty.