Re your question about top or bottom, most people would put the DB4e array at the top of the mast, and the Y5713 yagi further down. Supposedly this "looks right" ... plus the top 2 feet of the array can be above the end of the mast.
I mounted mine the opposite way, but my report indicates that my VHF reception is very very height dependent.
This is a DB8e and a Y10713. The other antenna is for FM.