Mike I have had PC routers for years and I bought the inlay kit years ago as well as a bushing / collar kit that was the threaded type. I don't even know if they had the other type then? I have found that most routers and bases are setup for these collars. I thing the other companies just designed their own system to get more of the market or whatever. The collars don't thread into the base though, they have a threaded retaining ring and the base is stepped. I can't say anything about the conical alinement tool but the Whiteside kit comes with an alinement or centering tool for it. And for using a 1/4" collar I'll use a 1/4" drill bit or rod. I'd put the whiteside collar and centering bit in the router and base plate when you mount the new base plate to the router as it should center the base from the start. I haven't changed out my base on my colt yet but I never had a problem with my PC bases being off. At least they line up dead nuts on. But it never hurts to check them when precision is needed.
I think that once you start using these collars and the concept clicks you'll see how usefull they can be. Just remember to keep the template to the right of the bit in the direction of travel. It will help to prevent the the router from drifting off the template and possibly cutting into your work. Depending whether the work is under the template or outside the template. But the point is it will help prevent drift from the template. But be aware that's when there isn't any material removed. If you have a wide groove and you are opening up a groove you might not want to be climb milling to open it up or the router could bite in and get away from you. You'll have to make that call depending on the amount of cut. Hope this makes sense?
