How can one reconcile commitment to religiosity, jurisprudential knowledge, and performing acts of obedience, with falling into sins such as enjoying foreign women for money and watching pornography, and the fear that this might be a contradiction leading to one's deeds becoming scattered dust?

The gate of repentance is open until the sun rises from the west. For sincere repentance from sins, you must reflect on Allah's blessings and show gratitude by using them in obedience to Him, beware of being gradually led astray, fear the disgrace of the Hereafter, and remember Allah's constant awareness of you.

Your commitment to congregational prayer in the mosque is one of the greatest means of guidance. Abandoning it is a grave sin, and it is better than a millionfold. As for devotion (khushu') in prayer, there are fatwas available to help with it.

Intentionally missing Fajr prayer is one of the gravest major sins. However, if you miss it due to sleep, there is no sin upon you, provided you take the necessary measures to wake up.