drilled nano

[Small Fry]

Hey all, planning to drill my 12 gal nano for fuge and sump, and am thinking i need four holes, to keep both systems seperate, just need some advice on where i should drill the holes, im planning on drilling three holes all together, one intake, split under the tank to go to both the sump and fuge, and then one return from each, but where is the best place to drill, just have one tower in the back center?? or two in the corners. Im just worried about the structual integrity of having holes drilled so close. And what sized holes/tubing would be best used i'm not thinking any more than an inch is needed, but am not totaly plumbing savvy

i just want to be sure on EVERYTHING before i start playing around with the tank

btw, i just figured out cutting out the back and having the overflows in the corner gives me an addition 1.75 gallons in the display tank

the way i have it worked out is there are two triangular overflows in the back corners of the tank, each with one intake and one return, the intakes will meet under the tank to equalize water flow from each corner and will go to its respective container.

I'm thinking if all pipes are 3/4" it will be alirght?? or does the intake have to be bigger than the return.

and if the two intakes are each three quarter inch pipes, does that mean when they meet they will have to be converted to a 1 1/2" pipe?? I'm using very basic knowledge and principle here so any help will be appreciated