A neat trick for applying sealant neatly, is to first stick parallel strips of masking tape to the wall and bath rim.  Then squeeze the sealant into teh gap between the two strip.  Smooth it with a ballpoint pen, and after about half an hour you can pull of the masking tap.

Baths usually come with an all-in-one hose and connector for the oveflow. The banjo end fits around the waste outlet, while the other end fits to the overflow opening near the rim of the bath.  Take due care to ensure that the hose inlet and waste outlet are properly aligned.

Thickness is important when choosing baths... the thickness of the bath mould that is.  Baths thinner than 4mm are vulnerable to distortion, so avoid them if you can.  Your best bet is a thickness in the region of 6mm.