Yep, I used to do with the ilife stuff without many problems.

You can do that, though it is likely easier to use https://github.com/maxschlapfer/MacAdminHelpers/tree/master/AppStoreExtract

the Apple ID for our VPP from which we bought all of our licences, doesn't seems to be able to redownload the app from the Mac App Store... its greyed out

Have a read through here for some options.