If I roll a critical hit with a character with either support or b/c/f, does that mean that I can apply an additional click of healing/damage to whatever I roll for healing/bcf(theoretically being able to heal/deal seven clicks), or do I only apply the extra click to that figure's damage value(and not if i roll??)???

Basically yes. But you always apply the critical first and then role to see what healing/damage will be done. You do not apply the roll and the critical at the same time.

I know critical hits add 1 to healing (it's in the rulebook) and I would assume this also applies to BCF (adds 1 to the damage roll) since the rules say to deliver 1 extra click to the damage.

Hmm....Are you sure about applying them at different times (the critical first, and then the b/c/f)...It doesn't matter for support if the clicks are applied at two different times, but for b/c/f that would allow powers like toughness, invuln, and imperv to activate twice, potentially reducing the damage dealt by three.......Opinions anyone??

Actually, I think you do. The rules say that the additional damage is added to the original damage. It doesn't make any difference on healing but may impact BCF versus someone with a defensive power.

AFAIK, all damage dealt in any single attack is applied at once, regardless of the source (the attack itself, knockback, critical hit, etc).

Ok....That makes sense...So to clarify, it is possible to heal or deal seven clicks based on a critical hit and a roll of six on the support/B/c/f roll......

Yes it is possible. All damage is applied in a lump sum, which is then checked against defensive powers. The only exception (which could apply since we're talking about a crit) is knockback damage, which is applied last. There was a very interesting thread here yesterday dealing with that topic. Essentially, you do your damage - in this case we'll say 7 for BCF+critical hit. If the poor figure has no Defensive powers, he will now be knocked back 7 squares, suffering an additional click if he hits a wall or 2 clicks if he falls off a roof. If the character has say Invul, 7-2=5 clicks, he then takes 5 squares of knockback. If he then hits the wall or falls off, at this point his Invul has already been "used up" for this action by reducing the base attack damage, so they will still suffer full falling/wall damage.

So theoretically, you can deal a max of 9 clicks of damage with a single BCF strike! Also, Logan/Spiral/etc. who have Flurry on that click can deal up to 16 damage, by critical hitting twice against a figure whose back is against the wall. BCF 6 + 1 critical + 1 knockback into wall = 8, which leaves the opponent still adjacent for the second Flurry to connect. Slice-n-Dice!!!!