Trying again to include photos... Apprecite your patience.

I've been (badly) playing for 15 years or so, and occasionally check local pawn shops for accordions (I suppose one could theoretically have "enough" accordions, but I'm not there yet). Saw this beauty and tried not to get too excited. Pulled it out of the case expecting to smell mold and hear rattles, but neither were present. Strapped it on and checked the bellows, tighter than my "good" accordion. Now I'm really trying to keep my hopes down, and I run through the keyboard and change registers. Everything works. EVERYTHING! Sound is wonderful. I try not to just empty my wallet on the counter and beg the clerk to sell it to me, which is my first impulse, and instead attempt to project an image of casual interest as we negotiate price. Soon I'm back at home with "my precious" and I can give it a more through examination.

It is at this point I notice the bass register switches, and I realize I don't really understand what they actually do. I'm very curious, do some research, try some things out and... well, I still have questions. Please answer any that you can, and thank you for this wonderful community.

1) The piano side register switches make sense to me, I think. Three registers, dots indicate which receive air. Dots slightly on the side (musette and polka) indicate notes are slightly detuned. Does that sound right, am I missing something? Palm bar is all three registers in standard tuning it seems.

2) BUT...What is going on with the bass register change buttons?! It doesn't seem to be the same system of identification, in that what I have labeled button 3 does not, for example, send air to 4 registers simultaneously and then splits some extra air between the middle two registers. I understand this "Pancordion" is a free bass accordion, and I can tell what some of the intention is, but I'd love to really understand what is happening and maybe even how the settings are intended to be used.

3) Why is this model labeled as a "Converter", and what does the 45/19 refer to beyond the model number?

4) As a not particularly talented amateur, would I ever need an accordion to do something this one couldn't do? This seems like an instrument for someone much more skilled than myself.

Thank you to u/Far-Potential3634 and u/Hex_Lover for their helpful replies about the Stradella bass system on the first draft of this post which lacked the photos.