Opportunist says, 'remove any number of tokens'

Is this subject to the rule of 3? If not...

Also, Can someone like 'The Colonel' use both feats, Opportunist and Contingency plan, Charge up to someone and Con Plan his attack by +3, THEN roll and use Opportunist to add to the attack as needed?

(If so, these two feats may help save the Liberators )

Only combat values are subject to the rule of 3. Opportunist affects the attack roll.

You can CP your attack value by +3, make the attack then Opportunist the attack roll, yes.

Speedster beat me to the punch (I guess that's why he's called speedster).... when you using opportunist, the modification is not in fact subject to the rule of three. Attack roll is not a combat value. Technically, if you wanted to, if you perplexed your attack up 3 times and subtracted 5 tokens from opportunist.... you could have an 8 attack... roll a 4... and still hit a 20 defense.

To get a critical hit it says that you have to roll double sixes, so opportunist would not give you a critical hit unless you had And Stay Down or extraordinary day BFC card in play.

This is exactly right. If you use Opportunist tokens to increase a 10 to a 12, it doesn't make it a critical hit. In better terms, if you have a Thug trying to hit KC GL (needing like a 14 or something), a crit hit will hit him (because the rulebook says double sixes automatically hit), but if you rolled a 10, you'd have to use 4 tokens to get it to 14.
Of course, ASD and EOD are the exceptions because they say rolls of 11 or 12 are crit hits

Yes, that's true, but in the case of Extraordinary day if you roll a 10 and remove one token to get it up to an 11... it's not a critical hit... you actually have to roll and 11 for it to be a critical hit.