Try jacking up the rear and supporting on axle stands, do this as high as you can get them.
Pump the pedal until you get resistance, but do not press the pedal right to the floor.
Leave the car overnight, any air will settle in the back brakes.
In the morning bleed the brakes using a proper pressure bleed kit with a pressure feed off the spare tyre.
If you are still having problems then try swapping the bleed nipple from the old caliper onto the new one, i have had problems with poorly tappered bleed nipples in the past.
As for clamping brake hoses, of course you can, hasn't anyone read a workshop manual
