Trading as an LLC

[Ehab Tadrous]

If i am buying and flipping houses or doing all my transactions using my established LLC , do i have to have it registered with the IRS and have an EIN number ?

I also have to have all the money spent out of a business account or , my personal account could be fine , like a line of credit under my name , or that line of credit has to be under the LLC name

thanks in advance