upgrading to 7.7 (from 7.6)

Hello,

I was tasked with upgrading our NetBackup environment to 7.7.2. this is my first time ever upgrading NetBackup so my wish is to consult here on the forum and make sure I understood and know everything I should before I start.

Our environment consists of:
master server version 7.6.0.4 installed on windows server 2008R2 (VM).
media server - NetBackup appliance version 5230 2.6.0.4
Plugin server for vCenter (VM) - which I don't know much about or how relevant it is for the upgrade - either way it is not working properly.
opsCenter Version 7.6.0.2 installed on win Server 2008R2 (VM)

I was reading https://www.veritas.com/support/en_US/article.000040130 and https://www.veritas.com/support/en_US/article.000100611. and this is how I planed my upgrade so far:

• I should upgrade by order: opscenter, master, media and lastly the clients. 
• follow this guide before upgrading opscenter: http://www.veritas.com/docs/TECH211070
• before upgrading the it is recommended to follow this tech note to reduce upgrade time: https://www.veritas.com/support/en_US/article.TECH211811 
• catalog migration is unnecessary because I am upgrading from 7.6
• before upgrading master server- stop opscenter data collecting 
• running the setup on the master server is pretty straight forward just move forward accept the defaults and provide the information needed.
• upgrading the media appliance- move the installation packages to \\appliance\incoming_patches, close share and install after killing the services.
• upgrade the clients

Here are the files I downloaded  for the upgrade:

NetBackup_7.7.2_AIX64.tar.gz
NetBackup_7.7.2_CLIENTS1.tar.gz
NetBackup_7.7.2_CLIENTS2.tar.gz
NetBackup_7.7.2_Download_README-Info.txt
NetBackup_7.7.2_HPIA.tar.gz
NetBackup_7.7.2_LinuxR_x86_64.tar.gz
NetBackup_7.7.2_LinuxS_x86_64.tar.gz
NetBackup_7.7.2_LU_1of2.tar.gz
NetBackup_7.7.2_LU_2of2.tar.gz
NetBackup_7.7.2_Plugins.zip
NetBackup_7.7.2_Solaris_Sparc64.tar.gz
NetBackup_7.7.2_Solaris_x86.tar.gz
NetBackup_7.7.2_Win.zip
NetBackup_7.7.2_zLinuxR.tar.gz
NetBackup_7.7.2_zLinuxS.tar.gz
OpsCenter_7.7.2_Unix.tar.gz
OpsCenter_7.7.2_Win.zip

for the OpsCenter I will use: OpsCenter_7.7.2_Win.zip and for the master server: NetBackup_7.7.2_Win.zip

these are the questions I am left with:

1. what installation packages I should use for the appliance and clients? (windows clients mainly)
2. is there a way to push client upgrades from netbackup rather than install them one by one?
3. I should obviously not preform the upgrade of the media server while backups are being done and actually stop the services of the media server before performing the installation. Am I to stop them for the master and\or the opscenter as well before upgrading?
4. there is a section in the one upgrade guides about MSDP- we use the appliance deduplication. do I need to look at this section?
5. is there anything else I am missing\didn't notice\forget or should know about? 
6. what happens if I screw this up somehow? what is the worst case scenario and the likeliness of it to happen?

Thanks in advance for the help.