I would go with I7 because of the HT and increased cache, especially when you are working with so many (resource-heavy) programs.
Don't have enough experience with OC to include this as a factor.
Don't know how much difference there will be with 16GB and 32GB, but if you think the price is fair for the additional 16GB, then why not?
You are right you also have to think about if you want to run dual channel ram.
If the 16GB is in 2x8 module it might be more expensive to upgrade them to 2x16 later.
One thing that came to my mind is which sound card you are using? just thinking it might me worthwhile to get an external card instead of the on-board.