Age Appropriate Behaviour

On the forum I frequent most, The Nappy Network, like many parenting boards, there is a lot of talk about age appropriate behaviour. "At what age will my child do .... ?"

So now it's my turn.

My child doesn't seem to be developing on schedule.... certainly not on average with peers.

At what age will my child sit in a seat properly? I know plenty of others that can by this age, but I've certainly never seen it here.

At what age will my child tidy up toys when finished with them? I've been told such things are possible, but I rarely see it here, and when I do I'm really not sure it's deliberate.

Are children always so easily amused? We have a Tiny Love play-gym - my child will sit and kick or bang the foot / hand pad in order to play the same cycle of three tunes and lights over and over again. I've grown bored with it - am I just easily annoyed?

At what age will my child speak intelligibly? I hear grunts, moans, whinges and coos and squeals but it's hard to make out words.

My "child" is twenty-nine. Please tell me he'll reach these milestones soon?