A tuner should not count as a 'pedal'; it is a tool to keep in tune and does not alter, color, or enhance your bass signal in a creative way. The advantage to a tuner in a pedal format(as opposed to clip-on or something at the amp)is that it can be a mute button, and possibly power a few(but not too many)actual effects pedals. To start out with, yes, an affordable multi-FX is a great place to start so that you can experience the potential of several different things. Not all will be to your liking, of course, and with even the effects that you DO like, there will probably be better versions with better controls on stand-alone units by different manufacturers. Once you outgrow the multi, that's when the real fun(and loss of expendable income)begins. If you do just want to start out getting them one-by-one, by the bands you mentioned, a chorus pedal is probably the best choice for now. Depending on your amp, you can get dirt/grit/distortion from your amp, at least until you can spring for a buzz pedal. I personally don't understand why distortion for bass is such a big deal these days; yeah, it's certainly part of the sonic pallet, and I have plenty of such boxes myself, but I think as you start out with this stuff, a chorus is going to be much more useful. Buy as much as you can used, or borrow it.