Tube preamp reliability vs SS?

You can listen before 30 minutes, you don't have to wait that long. The warm up time, optimal performance, for tube gear varies depending on manufacturer. Changing out a tube will not void a warranty. It is pull out the old and plug in the new, simple as that. Now on a tube amplifier it may NOT be as simple as that as biasing is required and how biasing is performed varies among manufacturers'. It can be quite simple to a royal pain but this isn't about tube amplifiers.

Tube life? well that depends on the circuit. Conrad Johnson gear about every 2-3 years in my past experience with their older gear. Their newer preamps  running 4 hours a day I would venture about the same but it will vary on the quality of the tube used. Chinese tubes don't last in my experience, even some of the premium ones at those premium prices although some sound quite good. The better tubes are from the golden age of tube manufacturer from the 1930's through  the 1970's. These would be tubes made in Germany, UK, Holland, Canada and USA. Also some of the Russian tubes are also quite rugged and will last longer. The older the tubes, generally the more expensive they will be. There are many reputable tube vendors to purchase tubes from as well as the manufacturer. A further word about tube preamplifiers, don't worry, be happy. They are as reliable as SS. I have been using tube pre-amplifiers exclusively for the past 30 years and have NEVER had any problem other than replacing tubes and an occasional fuse and I must say they are fun to own. You can try different tubes to suit your tastes but you don't have to.

"Would running low freq music, heavy bass techno etc etc through system break in the capacitors at all on preamp? Adding more bass overall???"

A very good question, I really have no idea as to how that might affect the capacitor break in, Al or Ralph might weigh in here. I DO know first hand that teflon capacitors take a while to settle in. NOW getting back to what Charles said about power supplies and how they make a difference, I couldn't agree more and it is something you should also pay particular attention to if you really want that bass to come through naturally and well articulated along with the amp/speaker interface. Power supplies are probably the biggest difference in adding a more effortless, natural and larger presentation of the music without it congealing and sounding too LOUD. They ALSO add to the cost. You might also consider  integrating a quality subwoofer as well for your music of  choice. 

"Musicians love tube amps since tubes are easy to replace. Semiconductors failure is harder to diagnose and usually require professional repair."

Not too sure about that Kijanki.  I would think it's more about the fact that the sound can be manipulated to achieve a desired result. At least that's the case with the one's that I've talked to. Plus most of the guys that use tube amps just like the sound, it gives them that "tube thing" that can't be replicated by SS. 2nd order distortions and all that makes tubes, well tubeelicious :)

Audio reproduction and tube guitar amplifiers have completely different objectives with one similarity, the preference for tubes in the circuit, it's simply a matter of taste.