I'm not sure if acrylic is easier to handle but I can't seem to use it good.
Basically, enamel is good for brush painting since it takes a longer time to cure, thus leaving no or little brush marks.
Ratio depends on how the result you want.. Maybe like 1:20.. For me, I will just shake the bottle and use the paint on the cap.. I don't even know if it is a correct way or not..

BTW, here are some tips to start with.
http://www.tamiya.com/english/scale/beginner2/index.htm
http://www.tamiya.com/english/howto/howto_top.htm