I surely missed this in forum mix of things … which is your native language?
For the rolling R, well, my native language - Slovene - is full of them in addition to Č (ch) Ž (something like “zh”??) and Š (sh). I wish I could help you in a way with that, but since it is so natural to say them to me I don’t find the way to explain things.
I agree with @Iestyn and his “rules” the most. …