I'm fairly new to Apple after decades of MS/PC. So, pardon my abject stupidity ... but can you elaborate a bit? My system is running great ... to the best of my meager knowledge ... everything except SMS seems to working on the MAC, all the continuity and handoff pieces are working ... should I re-download PB3? I know what a bootable USB is ... but ... how do I create one with the App Store re-download? And why is it important to the PB4 release? Help.
Sometimes explanations can make confusions worse, so I apologise in advance if the following happens to do that. It probably will. (But I think technology is particularly prone to this phenomenon).
As happened with PB2 and PB3, the next PB in the purchases tab
replaces the previous one. So it is important for PB3 to be there if a PB4 is released - even if you don't necessarily need to redownload PB3.
Recent disappearence of the PB3 from the purchases tab led to theorising that release of a golden master was imminent - but this was complicated by the fact that the developer previews DP1, DP5 and DP7 were still there. After several days of absence of PB3 from the purchases tab, it suddenly reappeared there with no explanation whatsoever from apple.
I made a thread on bootable usbs for yosemite public betas here:
https://forums.macrumors.com/threads/1757723/
If you installed yosemite directly from the installer without backing it up or making a bootable usb, then after installation, the installer deletes itself and you will be left with no backup of the installer. If you found this out the hard way and only subsequently feel you need to make a bootable usb, this alone will give you reason to redownload! I learned this lesson the hard way myself with Lion 10.7 and have been backing up full installers and making bootable usbs ever since. I even went back and made bootable usbs of 10.6, 10.5 and 10.4 because usbs install much faster than dvds.
I rarely need to use the usbs, but the few times I have needed them, by golly did I need them! And they did save my bacon. So although some will say it is a waste of money to spend a few dollars on a usb which you turn into a device capable of resurrecting a dead computer, that sure beats having a useless piece of hardware worth several thousand dollars!