Do you have a Verizon stb? If so, then that is probably what it is for.
Can't say. You will need to contact support for explanation as we here do not know the full details of your account.
Its the fee for 1tv. DVR charge is above and beyond the 1tv fee. The switched to charging for the number of tv outlets 1, 2,3, 4,etc and then the options for various DVR being additional quite awhile back. The DVR charge at least use to be 11 DVR, 12 MRDVR, 22 Fios enhanced TV(VMS) and 32 FIOS Premium TV(for 2 VMS)
I use to know where the chart was that listed the per room outlet and dvr costs, but I don't know if the moved it totally removed it.