Scope:
That type of question is indeed on topic here. (We even have a related promotion tag.)
Ask about:
- Creating, expanding, and cultivating communities, their content, and the relationships among members
Opinion based or not?
We have almost all "good subjective questions." A lot of building a community is based on experience.
Side note, the help center even touches on this "good subjective" type of question:
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than on facts, references, or specific expertise.
Anyway, questions one and three would totally fit, but question two is in a gray area. If you do ask that question, make sure to fill it with enough information that it's still possible to get answers based on experience in similar situations.
I might suggest asking the first question and adding "I've been thinking of doing XYZ, would this work? to the body instead of asking the second one.