What are possible drawbacks of using a company in Singapore for selling software online, targeting the clients in USA, EU and UK mainly - wrt the ease of doing business, possible double taxation, etc? (I'm not a citizen of any of those countries)
Sounds like a big question you'll probably need a lawyer and tax advisor that specialises in Singapore. What attracts you to there are you based there?
Well, I think that it's not some arcane knowledge that nobody but enlightened can understand. Anyway, it's better to collect some information before talking to them.
Singapore looks like a good location wrt taxes and ease of doing business, but I may be missing something.