If the talisman conditions are visible from the preview screen... do you think specifically showing the (remaining) limit in game on top of having the per-skill limits as suggested above... is necessary?
No, not at all. If it works in the same way as individual skill limits, i.e. changing colour or not allowing further skill assignments, this would be fine. It would need to be something in-game though, as it's way too easy to forget talisman info from the preview screen.
Let's just make sure I've been clear enough about what I mean here, because reading it again now I'm not sure I did clearly explain what I meant.
I'm referring to my earlier suggestion, re: "show the strictest limit that applies, and use a color to indicate whether it's a skillset limit, a talisman single-skill limit, or a talisman total-skills limit". If we have this, in combination with the preview screen explicitly showing "max skills", do you think this is good enough? Or do you think there should also be a dedicated in-level display for max skills?
There are cases where this would mean the max-total isn't immediately visible. For example, if a talisman restricts the player to 5 builders, 5 bashers, 8 total skills, then until the player has used 3 of one of the skills, there'd be no direct indication of the "8 total skills" (or the remaining portion thereof) - because it would be covered up by other, stricter limits.
Another option is to have a dedicated "maximum skills" field on the panel. In terms of positioning / space, there are several options:
a) It replaces (or displaces, possibly by introducing another top/bottom split panel similar to directional select buttons) one of the existing buttons when talisman mode is activated.
b) There's a permanent placeholder, possibly displayed with the "empty skill slot" graphic, that gets filled in when talisman mode is activated.
c) There's a permanent, non-placeholder space. This could either do nothing when not in talisman mode, or perhaps be used for a future feature that allows limiting max skills even outside of talismans. (Note that such a feature is not promised EVEN IF this display method is decided on in general. And I recall that this idea was suggested in the past and didn't have much support.)
or d) Use the info text area (I think I suggested this earlier). Whenever in talisman mode
and no lemming is mouseovered, display the max skill count in the area that displays info about the mouseovered lemming.
These are in order from hardest to easiest to implement. So the further up the list it is, the stronger support I'd need to see to go ahead with it. "Stronger" could be in terms of either numbers or reasoning.