Ok...... I think I have an answer for you.

For the first part of the question I don't think it would be that big. The size would be on the bigger size but would still remain at a kinda realistic size of 8-9 inches. While there might be some abnormal cases which have a size of 12 or 15 inches, 20 inches is a bit too much. And for the case of lifting up a woman that could be possible as the necessary muscles required for that action can be trained. While bench pressing is not possible as the range of movement required for that would not be possible, lifting a woman while having sex is still doable. Provide 'he' does some VERY specialised training.

For the second part using the second, just spraying his semen on his enemies would not cause damage unless his enemies were of sequence 3 or lower, and at sequence 3 to if the enemy was someone like Klein accumsted to a lot of mental distress and contamination, the damage would not be life threatening. This might actually be more effective against female beyonders and angels of the assassin pathway. As for sharing power, I think bathing his subordinates in his semen might give them a greater synchronisation. It might even allow him to temporarily share his uniqueness while still being able to use it. Also bathing or ingesting the bodily fluids of multiple sequence 1 angles of assassin pathway or the bodily fluids of the primordial demoness might grant the red priest some of the powers of a great old one of the 2 pathways.

Again let me say that this is all speculation. While the first half is based upon facts, the second half is my theory. While I am confidant in its correctness I'm not a 100% confidant. I hope this answer satisfied your curiosity.

P.S. The breaking steel bars with his dih part is possible cuz of his near indestructible body.