Hi Albert! Welcome! Nice axe!
I think the bump is an LED. Some of these were disabled by their owners because they drained precious battery power. I think they lit when a cord was plugged in.
The 'tone' knob is not actually what you're used to on other basses. Its a low pass filter that pretty much cuts off everything above the dialed in frequency. (As opposed to a tone knob that rolls off more and more mids and highs as you turn it down).
The blue things are gains on your pickups. If your pickups don't have quite the same output when you switch from one to the other, you could use the gain pots to balance them. IMHO, you get the best funk slap sound when the outputs are equal -- more natural cancellations of frequencies. But that's just one bass players opinion...
The three switches? My favorite part of my Distillate. One boosts and cuts bass frequencies, the center one boosts and cuts high frequencies (middle position is 0 gain), and the third, two position switch is the Q switch. There are others here that have described the frequencies of the boost and cut switches and the function of the Q swithch much better than I could. Try searching for Q swithch on this site for some great explanations. Try this: turn the Q on (towards the floor on mine), pluck the G string and let it ring while you turn the filter knob end to end.
She's a beauty. Take care of her.
Mark
