1) The flyer only uses a zorro slot and does not require a video slot.
2) Therefore you can use a RTG card in the second video slot (although many RTG cards only use zorro anyway).
3) Not necessarily, it may (and probably will) be an AT unit, with a Chinon FZ-357A HD floppy. This may have been supplied with the A4000T, or the original owner may just have upgraded at some point.
4) Don't know tbh.
5) SCSI2 HD50 - assuming the disk module is included with the A4000T package.
Regards
Rich