So the first thing to (unfortunately) keep in mind is that targeting works differently for Orders and Tactics Cards. For Tactics Cards, anything mentioned in bold before the colon (the trigger) is targeting. So, for example, the Free Folk tactics card "There's too Many!" targets the enemy performing a Panic Test, and thus couldn't be played on Lord Paramount's unit. Orders basically only target the unit with the order unless otherwise stated, so Set for Charge only targets the Halberdiers themselves. Yes, this is confusing, as they use the same format but have different targeting rules, but it's what we've got. With respect to your specific questions:
1. You can't use Boisterous Charisma to stop Set for Charge, or Ready! Aim! Fire!
2. Yes, because Counterplot targets you and your tactics card, not your unit.
3. For A Flayed Man Has No Secrets, it targets a unit that is concurrently being targeted by an ability or tactics card. So if you're targeting a unit other than Lord Paramount's unit with an ability from Renly's unit, then yes, AFMHNS could be used. If you're targeting Lord Paramount's unit with an ability or tactics card, then AFMHNS cannot be used as to do that it would have to target Lord Paramount's unit. In addition, I believe that since AFMHNS doesn't say "target" an enemy unit when expending the condition token, a condition token on Lord Paramount's unit could expended to make AFMHNS on another unit.
