Where is the earth absolutely flat? 
Nearly 1800 posts and you're still confused by the informal use of "flat" and "round" on this forum? Good fucking job.
[...]I have a few questions
Hi. Just to point it out, we have an
FAQ and a
Wiki that may be able to answer some (if not most) of your questions!
1. Why do people say the earth is round? It obviously isn't so what benefit is there in teaching our kids that it is?
It is likely the result of fake space travel. People thought the Earth was round, so they produced pictures of the round Earth as seen "from space", which has then been circle-referenced to finally "prove" the Earth round.
2. What shape is the earth? Like its obviously flat but is it a pizza shape? Or something like a square or triangle?
There is a lot of disagreement about this among FE'ers. Generally, the most widely-accepted shape of the
known Earth is very similar to the UN logo:

Other models exist. Here's an example:

Most of us openly admit that we don't know what exactly lies beyond the known Earth, so I doubt you'll get a definitive answer from anyone as to what the shape of the whole thing is. Some believe that the Earth is an infinite plane, but I think the general consensus is that it's a disc slightly larger than the known/mapped Earth.