I don't think you will get interesting results by asking these types of questions in this setting.
Firstly, you are asking questions about Swift developers and their employment in general, which no single subject will be able to answer without conducting their own survey. You'd just get anecdotal evidence.
Secondly, this forum will reach neither a big nor a representative sample of Swift developers.
I suggest you take a look at other surveys which have been conducted to find information about related subjects. The first one that comes to mind is probably the Stack Overflow Developer Survey, which (iirc) will give answers to at least some of your questions.