Neat. One suggestion - if you open all your DIP switches R2 is infinite and the output voltage tries to follow suit (crashing close to the input voltage), a bit nasty if you have a low voltage piece of kit on the breadboard. A solution is to have the highest voltage setting resistor permanently wired in place, then the DIP switches add resistors in parallel with it to reduce the vlaue for the other voltages - no more components and completely safe.
Yes, but that's a noisy switcher, not a nice quiet linear device :-)
Strange comment - with fundamental breadboard construction with lots of parallel bus-bars inside, any supply noise would be radiated everywhere. My preference would be to minimise noise inputs when using breadboards, otherwise you would spend all your time chasing artefacts instead of learning real things. IMHO.
Sorry to be pedantic, but this is a straight forward levitator, not a Levitron. A Levitron uses no power, just permanent magnets and suspends the spinning object above the main part of the kit.However, your is good too, just not a Levitron.
Being pedantic, this isn't a Tesla coil at all, it is a simple Induction Coil.A Tesla coil works on a totally different principle and generates far more spectacular results and is well worth taking the extra effort to make. Just Google Tesla Coils and you will find dozens of sites telling you how to make one.