What if one of the joint owner declared bankrupt? 

This is interesting. Maybe need property lawyer to answer this question. Also I would like to know for any particular property... what is the maximum number of joint owners?

I think there are no limits on the maximum number only the SPA will be messy with initials everywhere, as their shares should be distributed equally among them. Problem arise might somewhat be on the loan I guess. 

Let's get a legal expert and a banking expert to answer~

more joint owner... i believe can stretch the loan repayment tenure longer... up to 40 years perhaps? Good for investor going for Rental Yield returns. Rental able to cover monthly installment easier.

@Ace thanks for sharing