Am I permitted to lead people in prayer and deliver the sermon for the Friday prayer, knowing that I do not perform most of the weekly prayers?

Negligence in performing prayer is a great sin, and abandoning it is an even greater sin than other major transgressions. Therefore, sincere repentance and adherence to it are obligatory. The solution is not to abandon preaching, but to continue doing good deeds while correcting any shortcomings. The prayers of those who pray behind you are valid, according to the preponderant opinion, even if one dislikes praying behind a transgressor. We advise you to continue preaching, coupled with sincere repentance and adherence to the obligatory prayers.