For number 2, since the value can change over time as each entry is logged, seeing its value only when the file is created is not useful. Just add the V location as part of the log, that way you get the actual V value when that entry is logged.
For #1, we purposefully did not add a bunch of options to the instruction on purpose. It already has enough options. For full customization you can use STRPRINTs and FILEWRITE.