The buzzing noise that you’re hearing may be coming from loose parts or from small debris lodged in your aircon. It could also be because the wiring has gone bad. Whatever it is, you should take action right away to prevent further damage to your air conditioner.
A little bit of water leaking from the aircon is normal. Condensation forms on the evaporator of the AC as a by-product of its operation. However, if the leak is severe, there may be something wrong with your unit.
To put it simply, a window type aircon is easier to install, cheaper upfront, and easier to maintain versus a split type aircon. However, they tend to be noisier, slower to cool, and less aesthetically pleasing.