still a bit confused

[Vstar99]

Hello All
its hard for me to explain so i added a illustration to help me try to explain. http://develop.webheadgroup.com/naca/overflow_ill2.htm
for the pictures in URL you will find that I am having issues with entire set up. One of my hold ups is the overflow box. If i were to drill for bulkheads do i need anything else to go with it. 1 or 2 pipes. (clogging issues, etc.) Please take a look at the illustrations and thanks for your time and advice. - E!

p.s since all will be internal (in walls) right time the first time, if even possible