So much enthusiasm and many questions.Don't get hung up on sand - whatever works - works. If dirt creates problems - don't use it or get rid of it. Salt is the big problem - realise that most people think of the seashore when they think free sand. The cracks in the chapel were caused by some serious structure problems and too wet of a mix - they only occur to us because lime shrinks and sand does not - so cracks are caused by too little sand. Eventually you will learn this like cooking - you just know when its right.
Don't get hungup on magnesium either - it is superior to lime and can create hard spots - a minor worry structurally outdoors - a major worry if it will not absorb pigment.
Not sure if I want to hear the song - i compose songs for my dogs all the time so I know how they can get stuck in your head, and be a constant embarassment to those who love us. Sounds like hip hop?