Yes! The quintessential questions every player is trying to get answers for. IMHO good equipment is good equipment. Doesn't matter what it says on the nameplate, if it's class a, b etc. Those things matter, when you can feel the difference. I wouldn't say, that certain nuances are audible. I think you have to feel them, when you play them and therefore you have to try all this different stuff, or worst case, buy all this stuff. Good equipment is tricky to handle. That is what most tonehunters know and most of the gearnerd try to ignore. Every venue you place your amp and play is different. You yourself have to know, how your amp works, when there is a glass front, when you can turn the volume up, when there is wood on the stage that absorbs etc. Sorry for not really answering, but, the quest for the right equipment will never be accomplished, so just try to find an amp that says class a, play it a few months in different venues, think if you like it, otherwise try something else, if you can afford it.
Oh, the second question is more technical, so, just a short note:
point to point: soldering the single parts and connecting them via wire (?) and not placing them on a board with an outline of connections on it (not that technical, sorry).
bias: regulates the amount of electricity a tube becomes (please correct me!)