Night/IMC/Multi

[Ninj43]

Hi,

I have had a PPL for about 5 years and I am fancying doing something to further my experience.

I am looking at Night, IMC or possibly a multi rating.

Am I right in thinking that a Multi Rating is prohibitively expensive to keep current?

What are the rules for keeping it and the Night/IMC current?

Is there a minimum hours concern for any/all of these?

Thanks for any advice

Rgds

Ninj43