Ques. on Central Excise

I have few queries on Central Excise, which are as follows: -

Q.1 What will be the assessable value for levying excise duty if a manufacturer prints

different prices for different states or earmarks different packages for different areas     and marks different prices for different areas ?

Q.2 If assessee has cleared goods covered under sec.4A (MRP) without making payment of excise duty assuming (wrongly) that these are exempt. Whether he will get abatement of duty when he is reqd. to pay later?