Changing hard drive on Dimention 8400 Desktop

Thanks to all of you who respond to our cries for help.  I am going blind trying to find and read all the posts relevant to my situation.  Unfortunately, each situation seems to be different.

Here is mine.  I have a Dimension 8400 Desktop running XP SP3 Media Edition.  My BIOS is A07.  All of the cards on the motherboard are original.  I am running out of space on my C: drive.  I propose to install a Seagate Barracuda 1 TB internal drive as a second drive, plug it into the currently unused port on the motherboard (labelled 2), clone (using Acronis True Image) the current C: drive to the Seagate, then unplug the C: drive, plug the Seagate drive into the blue port on the mother board (labelled 0) and reboot.  I have no idea what will show in Setup at this point or what I will have to do.  When all this is working ok and I am sure the cloning worked, etc. I will install the original C: drive as a second drive in the port 2 postion, format it and use for additional storage.

My questions are:

Do I have to upgrade the BIOS to A09?  One post I've seen says no.

Will the 8400 support the 1 TB Seagate drive by directly plugging it into the motherboard or do I need to install a SATA II PCIe card?  Some posts say the 8400 won't support a 1 TB drive.  Other posts say it will.  Some imply that the PCIe card is required.

Will I have to go into Control Panel......Disk Management to assign a drive letter to the Seagate drive or will it pick up the next unused letter?

I'll probably have Setup questions later.

Thanks again,

Tom