'1. Is there a VDSL2 pilot tone?' Yes. It can carry data, modulated at 4-QAM, 2 bits per symbol.
2: Spectral mask - a list of tones to either be power limited or notched out entirely.
3. Nope the mask is to mitigate crosstalk with ADSL alongside avoiding certain frequencies already in use for other things.
4. The first part of the profile is how high the DSL goes bandwidth wise: 8, 17, 30, 35; the second a letter corresponding to a pre-built specification for the quantity, width, and frequency of each upstream and downstream band.
5. Not really. VDSL uses frequency division multiplexing, G.fast uses time division multiplexing so it's less profiles and more allocating time between the two directions.