I'm not exactly sure how the tights are worn - I see many of them are not padded: does it mean I need to wear my regular padded shorts underneath? Would it make sense just to buy padded tights?
It might or it might not. Padded tights mean you only have to wear the one garment, which is simpler . . . unless it gets warm enough for shorts alone and you're stuck wearing the tights because you've got no shorts underneath. With unpadded tights you wear the shorts underneath, exactly as you suggest, which lets you take off the tights, roll them up, and carry them in your jersey if the day gets warm enough. They certainly do make padded tights if you prefer, though.
You may also want to consider knee warmers. Worn with shorts they make a sort of poor man's tights (not quite as warm as actual tights), but when it warms up you can take them off and carry them much more easily (and they're cheap, relative to real tights).
Also, tights vs long bibs - any thoughts which are really better and why one vs the other?
Anyone could recommend any long padded bibs?
I've never worn bibs, but seemingly *everyone* who ever has loves them for their comfort. Inconvenient peeing (got to take off the jersey, apparently) and expense seem to be the only complaints.
OH YEAH, ALMOST FORGOT --- WHAT'S C H A M O I S?
Real chamois is a high grade of sheepskin if I'm not mistaken, and is seldom if ever used nowadays, again unless I'm mistaken. Now it more usually refers to the artificial padding in cycling shorts, which I believe is usually some kind of synthetic material such as polypropolene(?).