Remember that both types of track you're using were designed for HO standard gauge trains, not specifically for On30 narrow gauge. Bachmann uses code 100 track, Kato Unitrack is code 83. Code 83 is closer to the correct 1:87 scale size for most mainline trackage than code 100. Kato Unitrack is also narrower than most other brands of code 83 HO track, so is closer to scale size than most others.
Unless you've accidently damaged the joiners when pulling them apart or putting them together, there should be no problem with electrical connections for Kato track. As with any track, you do need to clean the railheads from time to time, and need several feeders (either the straight track with power connections or the wired track connectors.)