According to Wikipedia, Chasetown are the lowest ranked club to play in the Third Round, being in the eighth tier when in the FA Cup in 2007-08. If a Women's Premier League player is equivalent to a men's 10th tier, she could be good enough to play in round one and do OK.
But from the rules...
I've no idea either on this. Hopefully, someone on NSC does. I think it's safe to say that competing in the FA Cup is more likely to come before a FL or Premier League appearance.
You talk of women as one entity with one opinion. Surely they may be exceptions, especially with the financial rewards and prestige being mainly within the men's game?