1 My intuition says that early 20-year marriage brings more advantages than older one. The more older we are - the more dull, serious and conservative we become. I know many examples...
3 If you're dull age is only a second thing. You can be dull and conservative in your teen years and can be active, fun and romantic in your 50-s. It's all about personality.
4 It's difficult to say unambiguously is it good or bad to marry early. I have an aunt who married when she was 16. They have a great family! They have three daughters and they love each other strongly, it is apparently. It’s up to person would it be happy marriage or wouldn’t.
8 points 
1 My intuition says that early 20-year marriage brings more advantages than older one. The more older we are - the more dull, serious and conservative we become. I know many examples...