What you think you "need" is unimportant. What is important is what God has given you, because he knows much better than you what you need.
Now, as to your question: Jesus Christ is the one mediator with the Father. But all Christians are supposed to mediate for each other before the throne of Christ and through him to the Father, which is why Paul in several places asks others to pray for him. Evidently, he didn't think of the Christian faith as "Jesus and Paul alone", so why do you think of it as "Jesus and Senor Zorro alone"?
Precisely. He gave me ONE savior, ONE high priest, and ONE sacrifice--this suffices. I don't need your rosaries, your saints, or your priests. I need Christ--and I have him.
Overall, I think you very much miss my point. I am not saying that I don't want others' help (with Christ on my side, I will go without it if necessary), but I am saying that it is downright wrong to pray to dead saints pleading for intercession (see previous points). So, it is nice to have others praying for you and I know I have people praying for me, but not strictly necessary. I do not deny the efficacy of prayer by man (for it is written: "The prayer of a righteous man is powerful and effective." James 5:16 b), I deny the efficacy and the holiness of praying to man. Note one important thing about your own example: Paul asked those living to pray for him, not those who were dead.
"In God, whose word I praise, in God I trust; I will not be afraid. What can mortal man do to me?" Psalm 56:4
"For there is one God and one mediator between God and men, the man Christ Jesus," 1 Timothy 2:5
" A voice says, "Cry out." And I said, "What shall I cry?" "All men are like grass, and all their glory is like the flowers of the field." Isaiah 40:6
" Therefore, since we have a great high priest who has gone through the heavens, Jesus the Son of God, let us hold firmly to the faith we profess. For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one who has been tempted in every way, just as we are—yet was without sin. Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need." Hebrews 4:14-16 (emphasis mine).