Bought a new iMac to replace the old, Have a couple migration questions

My old iMac died — hard drive is on the fritz — and the system is mostly unusable.

I just received my new iMac and would like to know the proper way to do a couple things:

  1. Should I create a brand new Apple ID / login username or use the old?
  2. What is the best method for transferring my old files to the new iMac? I assume iCloud would be best since the old system is dead and I can’t use Migration Assistant. I did not have Time Machine backing up to an external drive.