I am connecting in Changi from a Silkair flight (Terminal 2) to BA in Terminal 1.

As Silkair is not part of One World, I assume I cannot check my bags at my original destination all the way through?

do I need to clear passport control, customs in Singapore?

Can I only use the transfer desk at Changi if I have hand luggage only? Or can they locate my luggage and transfer it onto the BA flight.

Thanks