Air in heating system that needs bleed in attic every day (Oil Boiler)?

Starters ~ I have a Camray 2 Oil fired boiler that appears to work OK. Problem 1 ~ When the boiler has been on, the radiators do not always heat up. I have bled each radiator, all OK. I have had to go into the attic and bleed the top valve ‘thing’ each day for the last week to get any heat through to radiators.
Problem 2 ~ The Radiator on the end of the system still gets very little heat. I have put the pump on a higher setting (because of this) and I can hear a lot of water gurgling ~ which I think causes Problem 1.
How do I clear the air completely and get my full heat circulating?

Sad Female