Okay, I have a couple of questions. To qualify for the Evangelist Prestige Class: To qualify to become an evangelist, a character must fulfill all of the following criteria.
Alignment: Within one step of chosen deity.
Deity: Must worship a single, specific deity.
Feat: Deific Obedience*
Special: Any one of the following:
base attack bonus +5
5 ranks in any skill other than Knowledge (religion), or
ability to cast 3rd-level spells.
You need to be 7th level bard to get a base attack bonus of +5, 5th level to get 5 ranks in a skill, or 7th level bard to cast 3rd level spells. Am I missing something?
As for getting you into the group, my choice would be to assume you were part of the original group prior to the events of the game and attained your Mythic status along with them, but have been tasked with something else by the queen and have just arrived to rejoin the current mission. That would simplify a lot of things. If it doesn't work for you we'll come up with something else.
I would prefer not to use third party spells or archetypes. There is so much official stuff for Pathfinder now, I just can't see a need to bring in outside material.