1. In the UK, none are correct. They should be:
a) Climb to altitude 4000 feet, QNH 1015.
b) Descend to altitude 4000 feet, QNH 999 millibars.
c) Climb flight level 230. (No 'to')
2. The rules of the air require aircraft to observe a speed limit of 250kt IAS below FL100.
The limit does not apply to:
a) Flights in class A and B airspace.
b) IFR in class C
c) Flights in class C & D when authorised by ATC.
d) Test flights iaw specified conditions
e) Flying displays authorised by CAA
f) A/c subject to written permission from CAA
g) A/c not subject to ANO (eg. military)
So, in your example, the limit is applicable.
3 & 4 left for those in the know.
Edit: Beaten to it!