"GVP HC+8 SCSI Controller with 4gb Harddrive CDROM 8mb RAM for Amiga 2000 4000"
Should be relative simple to install in any A2000
"Also, I found in amigakit a 4gb cf hard drive for a4000"
This is most likely IDE, the HC+8 controller is SCSI. and you would need a SCSI-IDE bridge in addition to the CF adapter. unless it is a SCSI-CF adapter. (they are RARE)
"Does it plugin externally or do I need to open my amiga 2000?"
You need to open up your A200 and install the controller into one of the ZORRO slots.
All though, the card do provide an axternal SCSI connector for external devices. Like the external SCSI ZIP drive. Or JAZZ drive if you have one of those.
"I cannot buy the hd on ebay now, but a few months in the future I can buy it?"
No problem as long as it is a SCSI drive you plan to purchase....
SCSI to SD bridge may be a viable option for your system using the HC+8 controller.
"The cf hd from amigakit is very inexpensive, but i dunno if it will work on a2000 or If I will
be able to install myself."
you have to make sure it is a SCSI adapter. or it will not work....
A400 has an internal onboard IDE controller. The A2000 does not. And your HC+8 controller is SCSI
If you have not seen the hardware database yet. have a look
HERE