There are a lot of questions here, so I'm going to start with the two examples given and just add my two cents.
In the first case, I think you have to keep in mind that ideas are very representative to Fe-Ti of the people who make them. Just as you would show caution as a Fi-Te user about telling someone that their feelings are offensive and unreasonable to you, you need to show caution as here. He had put a lot of work into what he was doing and probably felt either attached to his position or embarrassed when you pointed out the problem.
Therefore, instead of going at the idea directly, you need to point out how it would be to the other person's advantage to consider an aspect that they might not have thought about rather than going at it head on. This may seem like selling out to you, but if the issue is getting him to understand why his decision was inappropriate, this is the way that you have the most success of actually making him think differently about it. It would be important to first understand why they had chosen to make it a men only event (would men be more receptive to the information/activity if it was only men there, were their multiple goals trying to be accomplished, was it a way of making a more homogenous group to work together?). When you understand the other person's reasoning and determine whether it is a deeply held position, thoughtlessness, or a need of additional insight, you can go into the situation in a much more informed manner. It tells you from what direction you need to approach the argument and also keeps you from immediately being discredited by the other person, who feels that you are just projecting your own thoughts or beliefs on them without taking time to understand that they had reasoning too. You may also point out the personal implications that person's decision might have or how their organization could be negatively perceived by making it a mens-only event.
When it comes down to it, unless you are a close friend or a very highly respected colleague, they don't care what your strongly held values are. You need to try to step into their shoes and understand why they chose as they did, and then explain how your strongly held values could be important for them to consider. Also avoid using too forceful of language and give them a couple of days to think it over. It seems counter-intuitive, but will actually make success much more likely.
I realize that to Fi these issues are a matter of conscience and it seems smarmy to paint them as anything but that. I'm not advocating being dishonest, but rather trying to see things through their eyes. A ball of tangled and knotted string only gets worse when you pull on it and try to fix it immediately; you need to take the time to see where the tangles are and slowly pull them loose. Similarly, I think you only discourage or exasperate someone if you come on too forcefully without taking time to see where the "tangles" are from their perspective and address them before suggesting your solution.
With the second situation, I think that is just an example of someone being a busybody and a jerk. Each type has predictable generalized ways of interacting in healthy ways. While certain unhealthy thoughts or actions may be expressed in a particular way by each type (eg some are more likely to withdraw, others only show their strong side, some manipulate, etc), those unhealthy actions are not really a central part of people that type. Obviously, it is your right to reject any suitor that you please. If I were trying to be the rejected suitor's loyal friend, I probably would refrain from socializing a lot with you until the sting of the rejection had worn off for my friend and he had moved on. However, this is just a case of the "loyal friend" taking matters into his own hands and maybe even being counter-productive to his own friend's success. Who knows what all is at play here. You have to take into account the health of the individual, age, maturity level, history and so on. I don't think you're going to find a lot of NFJs on here saying that they think this is good behaviour.
It is however, an example of Fe's ability to create an emotional atmosphere and not just to make everyone be nicey nice. Like unhealthy Fi, unhealthy Fe is destructive as well. I think it is important to compare healthy Fe to healthy Fi to understand differences, vs unhealthy Fe to healthy Fi. Does that make sense?