IPS manual signatures

Hello,

My client's  fortigate does not have Internet connection so i have to update the ips signatures manually. FGT is running on 5.6.2

I think i have to download the ips signatures from support site (support.fortinet.com) and download that into the FGT. Can someone confirm this for me please.

If this is the process, where should i go in support site to download the ips signatures ?

Do the ips signature file based on FortiOS version or Irrespective of what FortiOS running on the FGT any latest ips signature file  should be compatible ? In other wards for a 5.6.2 FGT do i have to look for a specific ips signature file or can i download the whatever the latest signature file ?

Does the FGT get rebooted if i manually upload the ips signature file ?

Do i have to consider anything before doing this upload ?

What would be the downtime if i do a manual ips update ?

Thanks for your help.

Narendran