If it's changing your own name that's appalling that you can't call yourself what you like.
Sadly not, or at least if you want people to recognise it formally, like banks etc.
That would mean if you were divorcing and you had taken your husband's name on marriage but wanted to revert to your original name or something else you'd have to get his permission until the divorce is final.
That is correct.
If you are married, unless you have a formal separation agreement (in which case you only have to inform him), then you need your spouse's permission to change your name.
You do not need permission on divorce though, nor post divorce.
I think, but might be wrong, this only applies to women, I think men can do it without permission. But maybe that just never happens.
My sister has just been through this - her ex left her in March 2016, they've not divorced yet and she wanted to change her name and she had to get his permission.