I've made a number of interchangeable barrels for my high wall, low wall (both "walls" are coil spring), Rolling Block #5 with straight extractor, and four Martini Cadets.  I rotate barrels frequently with no major tools - I use a rubber padded vice and 24" clamp bar.  All have used take-off barrels that I re-chamber or line, so I am setting headspace for the action it is mounted to.  I hand tighten them all, and some even require a couple of wraps with oil-soaked thread to get a snug fit.  I made the fore stocks a very snug fit to the receiver for added stability.  All of these rifles require the extractor to be properly centered/clocked or they will not cycle, making it virtually impossible to load/fire without proper alignment.  Been doing it for 5 years and no problems.  My collection of barrels is at 22 and growing, with some interesting calibers.  Basing caliber selection on a family of cartridges with a common rim diameter (ie:30-30, 25-35, 32-40, 35-30 and 38-55; 32-20, 25-20, 218 Bee, and 222 rimmed) makes the extractor issue easier.  Also, putting scope mounts slightly forward of the receiver means you don't have to remove them when you switch barrels.  Hope this helps.

It really just comes down to what one has total confidence in and if it works it won't be the wrong way. Even the various top Jacketed Benchrest gunsmiths have their own way of approaching it.

Yes I used Teflon Tape on my original CPA's barrel threads and I found it to be a benefit for myself. I now cut my own threads and the fit is not as generously loose so I haven't found a need to continue to use it on those that I cut myself.