everfresh

uncheck auto-normalize. since you only have painted weights to one joint, you cannot subtract any weights when normalize is checked, since normalize makes sure the sum of all weights is 100%...

something went wrong with the weighting, some of your points don't add up to 100% in total. bring up your weights manager and hit the normalize button, most of the time that fixes it. 

ah, i did not think of that.... if you just add a pole, you can tweak the position of the pole vector so there's no visible stretch or squash.
fold_02.c4d

you need to scale the elbow/knee controllers and advanced bend controls in local z (object mode, don‘t use model mode to scale anything in a rig)) to get the tangents for the bends, then you rotate for the angle... don‘t unlock the positions for the advanced bend controls , there‘s a reason i‘ve locked them 😉 i recommend watching the tutorials to save you trouble like this.

you just need to put it on the right joint....  constrain the glasses to the head joint of the t-pose rig, which is what the character is bound to. set priority to expression 0 or 1 or anything above 0 and it will work.

you can easily use the stand alone facerig with the advanced biped, you won't face any problems (pun intended), is was made for that purpose.

although the toon rig is made for toon characters, it also can handle realistic characters, you just then don't use any of the stretchy/bendy features.
 
so what you decide to use mainly comes down to your personal preferences. feature wise the face rigs are more or less on par, there's slight differences in functionality and setup though...
there are examples in the content browser for the toon rig and the face rig, just give them a spin and see which one you like better.
 
the body rig of the toon rig preset has a bit more features than the advanced biped, apart from the squetchy and bendy features there are a couple of handy space switches and some other things the advanced biped doesn't have. for instance the hand gizmo makes it very fast and comfortable to get nice finger poses with a single controller. also it's a little bit faster than the advanced biped.

those are all the major differences i can think of, both are good stable rigs. again, in the end it comes down to personal preferences.