newbie piping questions - what size return - what size overflow?

[Milad]

is 1.5 a weird diameter? im not 100% sure what they are im going by what i remember when i saw the tank. I wont have it until 1.5 weeks from now. They could have been 2"

I just want to make sure there is a backup for the backup. I would die if 180g of water went everywhere!

bloodasp suggestion doesnt look to bad i just dont know if its going to pull in the same water it returned or not.

i could just plug the existing holes and drill 3 new holes...

this is hard setting it up as a peninsula, very little to work with.