very easy to do if you do it right, just take time to line them up perfect, and if you need too just take a chisle or knife or something and just file down the edge
i know what you mean but im not sure that will help much at all but i may be wrong (proboly am). i think it'll be the same as if there just straight up and not cut at the 45 it'll just be at an agle rather then straight up and down would it make a differnce? just tell me if im wrong haha you can be a dick if needed
make the 2nd portion a little bit lower. if its only like a half inch or so it shouldnt affect your slides, and you wont catch the edge at the connection.