It depends on when I am cuebidding it.  If it is late in the auction and we are looking for slam, then I will be showing either first or 2nd round control for my cuebid.  So I could have anything from void to A or K with some number of them.

Cuebids come in many forms so there is no definite answer to your question.  Most players use a cuebid as the only forcing bid after an overcall, and it says nothing about the suit being cuebid.  Many players use a cuebid as a limit raise over an overcall, and it says nothing about the suit being cuebid.  Sometimes it is asking or showing a control for a nt contract.  At a higher level it could be a control bid looking for a slam.  And then there is Michaels and all it's variations.  Again, says nothing about the suit being cuebid. (except you'd better be pretty short or you are lying about your Michaels bid).

 

So there is no rule about how many cards you can have.

Pass    <o:p></o:p>

   Pass      1C        1H        Pass    <o:p></o:p>

   2C        Dbl       Pass      4C      <o:p></o:p>

  In this bidding sequence 2 clubs shows support for partner's hearts but doesn't say anything about the number of clubs. I cannot assume there is a singleton or doubleton club?

I would tend to assume a singleton (if not a void) based on the rest of the auction if I were looking at 2 or 3 clubs.