Welcome @LiLiT. I have no answer for your first question but I have my opinion about second one.
It is very simple
good user experience = satisfied user = a couple of new users (recommended by the first one) = more money
But the tough part is to find the proportion of investments (time, money, possibilities…) in good UX and the expected outcome.
Also there is a difficulty with business people as they count everything money-wise.
What is the actual ROI of the 3 days of development of a new feature with a great user experience?
If we don’t develop that feature will any user stop using our service?
These kind of questions are really not easy to answer at all. So if you don’t have a financial proposition you can’t push your UX improvements.
UX investments are not returning quickly, but they have potential to even multiply your income (despite what type of income we are talking about).