A 188 No.
If you are able to take only a standard action or a move action on your turn, you can still charge, but you are only allowed to move up to your speed (instead of up to double your speed). You can’t use this option unless you are restricted to taking only a standard action or move action on your turn.
When you cast Celerity outside your turn, you're not restricted to taking only a standard action on your turn; you're restricted to taking a standard action out of turn.

A 189 No.
Quote Originally Posted by Shapechange
This spell functions like polymorph, except that it enables you to assume the form of any single nonunique creature (of any type) from Fine to Colossal size.
Quote Originally Posted by Polymorph
The assumed form can’t have more Hit Dice than your caster level (or the subject’s HD, whichever is lower), to a maximum of 15 HD at 15th level.
Shapechange inherits the HD limitation of Polymorph.