Hi again,
Have you done the head gasket test yet? I ask as what you are now describing is classic of a blown head gasket - it is 2 fold, firstly it keeps putting air into the coolant system and secondly it creates very high pressure in it - we are talking about cylinder head combustion pressure bleeding into a system designed to take gas expansion due to heat the result is the rad cap gives or it keeps blowing pipes off.
You keep finding leaks and when you fix them you get blow off from the rad cap - I strongly suggest you test for a blown gasket there is a good chance if you catch it now new gaskets will save you maybe a quick skim, leave it and you may well blow your engine.
Just my tuppence worth, hate to see this get worse.
Keyser