Problems Updating/Patching SAP Installation Server

Hello,

i have some questions about the SAP Installation Server SAP (SAP GUI for Windows 7.10)

1. can i install two SAP Installtion Servers on the same system (for example SAP GUI 7.10 and 7.20)?

2. is there a dedicated deinstallation routine for SAP Installations Server (i found none) or can i just delete the installation path?

3. can i update Installtion Server SAP GUI 7.10 to SAP GUI 7.20 by a patch or something?

4. i tried to patch SAP Installtion Server by using the "Patch Server Button" form level 10 to 14 and 15. At both times the patch was successfully verified; but after the automatic restart of the Installation Server and the selection of the installation path, nothing happend.

5 and least: can i Install the SAP Installation Server on maschine running a SAP System (for example ECC 6.0) on?

i know.. many questions, but our company needs to upgrade form Installation Server SAP GUI 7.10 to SAP GUI 7.20.

Thanks and best regards

Andre