128:6 The one leading the selichos wraps himself in a tallis before starting with Ashrei. There is a doubt as to whether or not one should recite a bracha on his tallis when putting it on at night, so he should not use his own tallis, nor one belonging to the shul. Rather, he should borrow a tallis from another person. If there is no tallis available, he says selichos and the Thirteen Attributes of Mercy without a tallis. (If only his own tallis is available, he wears it without a bracha. Once it gets light, he should handle the tzitzis and then recite the bracha – Shaar HaTziyon 581:5.) In some communities, the practice is that the one saying selichos also leads shacharis and mincha, as well as maariv on the preceding evening. He even takes priority over a mourner, a mohel on the day of a bris and one who has yahrzeit. (Mishnah Brurah 581:14 cites an opinion that one who is fasting on a yahrtzeit takes precedence; a mourner should take over when they reach Lamnatzeiach.) It is best to stand while saying selichos but if this is too difficult for one, he should at least stand while saying “(k)Eil Melech yosheiv…” (“Almighty King, Who sits on the throne of mercy…”) and the Thirteen Attributes of Mercy.
128:7 We should be careful in selecting the one to lead selichos and the High Holiday prayers that the person chosen is appropriate, a Torah scholar, and one known for his good deeds, to the extent that such a person is able to be found. He should be at least thirty years old because by then, his youthful hot-bloodedness will have died down and he should be in control of his passions. He should also be married with children because such a person will pour out his heart and seek mercy from the bottom of his heart. (If the only choices are a single, G-d-fearing Torah scholar under thirty and a simple Jews who is married and over thirty, priority should be given to the scholar – Mishnah Brurah 581:13.)
Similarly, one should carefully select the person to blow the shofar on Rosh Hashana and the one who prompts the shofar-blower. They should be G-d-fearing Torah scholars to the extent that such people can be found. However, any Jew is fit to carry out any of these tasks so long as he is acceptable to the congregation. If one sees that fights are breaking out because of his appointment, he should step down, even if his replacement is somehow less worthy.