Whether IP Board, XenForo, or vBulletin, you should plan on paying for ongoing updates and patches. It may not be the same as IPB's annual renewal, but you will likely have an annual cost of some sort.
Most software will have bug fixes issued from time to time, and the Internet has become a...
Yes, I did a fair amount of development to integrate an event calendar and casino list into the forum software. There's a learning curve of course (isn't there always!), but once you get the hang of it, the structure is really quite impressive.