People like to collect the relics of Saints for pretty much the same reason that people collect memorabilia of actors and rock stars - adoration of celebrities. If it motivates their devotion to God, then great, otherwise it is a distraction, and in some borders on idolatry.
No. The Holy Spirit provides all the help we need in prayer, interceding for us when we don't know what to pray ourselves.
"Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered." - Romans 8:26