>>329287884
64 GB is fine. 
Don't get the official strap, get a third party option. 
Extra face pads aren't necessary but can be beneficial.
For both of these things just try the default headset out first and see what the comfort is like for you personally. 
To use it with a PC you'll need either a USB 3.0 type C cable or good 5 GHz wireless router + Virtual Desktop. 
And don't forget the Facebook account is required to login to use the headset although you can use MAC address filtering or PiHole afterwards, plus manual firmware upgrades/downgrades, for complete permanent disconnection from Facebook servers.