transformation confusions

I wonder if someone would have time to clear up some confusions for me please?

1. The Vphot admin page allows input of several TC's - do the 'Filter band coefficients' equate to Tv Tb and Tr etc?
2. I assume the 'colour index coefficients' are self explanatory (e.g. Tbv for b-v)
3. I am most confused however with Tv, Tb etc - surely these will be airmass dependant if they are simply slope of for example Tv (catalogue Vmag - measured vmag) versus CB-CV.
4. I don't get airmass in my fits but i see vphot calculates it - however, this calculated airmass is not translated to reports for time series I do - is it possible to have the calculated airmass tranferred to time series reports?

Thanks in advance if anyone has the time,

Regards

Martyn