Backuping our Farm and site collections, are we doing things correctly

We have a sharepoint enterprise farm 2013. and we are reviewing our sharepoint backup policies. currently we are doing the following backup tasks:-

1. Every day @4 am we backup our farm:-

Backup-SPFarm -Directory  \\fileserv\Back -BackupMethod full -BackupThreads 10 -Force

2. Also we backup our site collections seperately:-

backup-spsite  http://w*****1/ -Path C:\Back\home.bak
backup-spsite  http://w****1/depts/ -Path C:\Back\depts.bak

Now my question is about how we can restore these backup files, so i have the following questions:-

1. as per my knowledge to be able to restore our farm or our site collections, the destination farm should have the same farm build number. so let say our sharepoint server OR our sharepoint database server had a sever hardware problem, and we were not able to work on it again. and we had to build a new sharepoint farm. so in this case we need to build a new sharepoint farm >> install the sharepoint updates to upgrade it to the same build number as in the source farm >> then restore the farm backup files? will this work on paper? My concern is that; as per my knowledge that 2 farms can have the same build number , but can reach the build number from different patches.. so how we can manage this? For example, on some farms, our customers install security updates for sharepoint , which sometimes upgrade the farm build number, while other customers only install full cumulative updates. but the farm which have a full CU installed and the farm which only have some sharepoint security updates installed , might have the same build number. so in this case if we have a farm back up files, then how we can reproduce an exact farm to be able to restore the farm backup files?

2. Second question. If we have a farm backup files generated from this script:-

Backup-SPFarm -Directory  \\fileserv\Back -BackupMethod full -BackupThreads 10 -Forc

then can we restore the farm backup files on a farm which have a higher build number compared to the source farm? or can we restore the farm backup files on a farm which have the same build number as the source regardless of the patches that are installed?

Thanks