I think that getting the first two is already great, but I am 1100.
I would suggest you to share directly here one or all three positions that you find hard to understand, with their diagram; people tend to be happy to explain when the question is put easily and people do not have to click on other three pages to see what you are referring to. Ah... we are all a bit lazy and with different degrees of an attention desorder. 
It's difficult to keep focused when there's too much input!
Hello! I recently hit 1600 ELO and embarrassingly enough, I have never studied endgames before. I just found them boring. But now it's the time to fill in this huge gap in my knowledge.
I stumbled across the Winning Rook Endings section here on Chess.com. By studying endgames basics (e.g. Lucena position) I was able to consistently win the positions 1 and 2. Position 3 I find much harder (my success rate is probably 5%). Position 4 and 5 I find ridiculously hard and was never able to get the win.
For the first three positions, I have found sound principles that I can rely on. For positions 4 and 5 I am completely clueless. I don't really know where to start. Does anyone have any suggestions on positions 4 and 5? I am wondering if this is the time for me to pay a coach.