Vbytes is a more recent estimation that still counts in bytes, but does not count the bytes of certain parts of the transaction such as the witness data (IIRC).
It does.
Virtual size is transaction weight divided by 4 and weight is counting witness by computing "base size" (which is serialized size without witness) multiplied by 3 added to the "total size" (which is serialized size with witness).
FYI: Just now I have incorporated your definition as a revision in the
Satoshi per byte wiki page.
People here are saying the protocol is getting harder / softer towards allowing stuff respectively, but my observations show that protocol development has pretty much been almost a deadweight as hardly anything changes inside of it.
That isn't to say that it's becoming harder, because it has really been at "almost impossible" for a long time now, but expect to see 5+ year wait times if you want your feature added into the protocol.