I always think of praise songs as being fast and worship as being slow, but I know that that's not always the case. Praise: giving thanks to God for his acts (what He's done), and worship: appreciating Him for His immutable attributes (who He is...essentially).
As for the 2nd question. I really think there's a definite difference b/w tradtional and hymns. I think of traditional songs as being short choruses that most Christians know i.e. I Love You Lord, Bless the Lord Oh My Soul, The Blood Will Never Lose its Power...Andrae Crouch-type stuff
. Whereas hymns are like you know, John Wesley, Isaac Newton, Fanny Crosby etc.
