1. For getting the value of the variable you can use the variable name inside dollar expansion like $(varToday) in a text object or anything else.
2. You can use condition like If($(File1)<Today(),$(File1),Today())
File1 has the text upper(date(if(match(num(weekday('$(varToday)')),0,1),'$(varToday)'-4,'$(varToday)'-2), 'DDMMM')) if you used SET keyword before it.If you use LET then it has the value returned by the method.
LET computes the value and set to the variable.
SET set the value as expression you assigned and you need to compute it using $(=varToday).