Is there a problem with acting more stringently in halacha than your Rebbe acts?
If so, what if you are not in front of your Rebbe?
If so (to #1), is having a longer beard or peyos considered a problem? (Even if that's not a stringency, the reason behind not acting stringently in front of your Rebbe could (maybe) apply to things that are not technically a stringency.)
If I were to break down this question to its bare essentials, I would ask: Does the rabbi make the Jew, or does the Jew make the rabbi? In other words, if we see our life as a journey in which we try to move spiritually upon our current plane and attempt to raise ourselves to new levels, can it be that the rabbi who started us on our path is the one with whom we will finish? Not always, as I will explain below.
My second question focuses on #3: Is it the beard that makes the Jew or is it the Jew who makes the beard? I will explain that, also.
Pirkei Avos 1:6 quotes Rabbi Yehoshua ben Perachiah saying: "Obtain a teacher for yourself, acquire a friend for yourself, and judge everyone favorably." These words are a recipe for success: One should always have a teacher -- a rabbi -- who can be a source of spiritual power that enlightens his way and provides strength as need. Similarly, the friend plays an important role in creating positive reenforcement and a supportive environment. Without both, a good teacher and a friend, the Jew has focus and direction in life.
If one looks at the original Hebrew of this teaching, though, it literally reads in Hebrew, "Make a teacher." Rabbi Zalman Baruch Melamed writes, you should always have a teacher, and even if your teacher isn't someone who "appears to be a 'messenger from the Almighty' Himself; even if he is not the most faultless individual on earth, one should not remain without a rabbi." But that raises the question of what do you do when you actually find someone who strikes you as a "messenger from the Almighty"? Do you stay with your old rebbe who cannot meet that standard, or do you move on? I think since the halacha here is that we make the rabbi, we are not required to remain with the same Rav when our soul requires something better.
But as we learn from Yaakov Avinu's vision of the ladder, Gen. 28:12, our spiritual lives are not, and should not be static -- we should be at least trying to rise up the ladder, otherwise we will be pushed down by those trodding upwards. If our rabbi is only able to move us ten or twelve rungs up the ladder, and no more, and we've reached that level, why must we stop there? Find a new guiding light to move up more.
There is a famous story about the Satmar Rebbe, Rabbi Yoel Teitelbaum, zt'l. After the war, a Holocaust survivor, R. Elimelech (Mike) Tress, who knew him before the war, would often come to visit and the Rebbe would treat him with great honor. But the Rebbe's students wondered why a man without a beard would command such respect from the Rebbe when Hasidic custom requires men to be unshaven. The Rebbe responded: “In the World to Come when Mike Tress gets there they will ask him, 'Yid, Yid where is your beard?' When you get there, they will ask 'beard, beard, where is your Yid?!'" In other words, if the only thing the Satan has against you on your Judgment Day is that you failed to grow a beard, you're doing OK. Conversely, if the only merit you have is that you did grow a beard, but made many wrong choices, then the beard is a weak defense.
When I was in the conversion process all new comers to shul will think I was the shul's Rabbi as I habe a natural beard but his was trimmed. Of course the impression wouldn't last as my lack of Hebrew have me away. It wasn't my idea to look more Jewish than most congregants buti felt not looking Jewish enough was hindering and slowing the process. I never asked my Rabbi if it bothered him. Later on I moved to a different shul. My beard and peyot were longer than the Rabbi's. I did ask if out was ok how my peyot were as I heard him couple of times advocating for natural beard. He told me was fine. The bigger the better. And it isn't a Yemenite or chassidic community. So ask your Rab instead👍.