I work with Ti all day long (castings, but same idea). Welding Ti is not as hard as welding aluminum even, but Ti has to be welded in an inert atmosphere. Not even really that big of a deal, but again its just knowing whats going to be required and being familiar with the type of welding.
As far as heat treat and all of that goes, I dont know. It depends on the alloy of the Ti.
In short, if you really want to do it, talk it over with the maker first, and find out as much as you can. Then hopefully you have a good assortment of welders to hunt through and find someone thats familiar with welding Ti.