With the lower arm ... you are in a hopeless situation
So you could not separate it ... so you undone the circlip .. bashed it out and hack-sawed it off the lower arm.
Too late now - so looks like you have no tools at all ... you needed a ball joint separator.
https://www.ebay.co.uk/itm/135308467889?
or this
https://www.ebay.co.uk/itm/276635068889?
its on a taper on the lower arm and would have to be bashed upwards .......
you've got no chance! unless you take the lower arm off and put it in a vice.
Then you may as well replace the whole of the lower arm ... as you'll probably damage that beyond saving getting that off .
Getting the lower arm off can be more painful than what you have just done, if you have rust plus I believe when its bad with rust, the captive nuts turn inside the chassis legs... then you are royally stuffed!
So new lower arm needed .
You'll need this tool to get the new ball joint back into the knuckle . difficult and very hard.
https://www.ebay.co.uk/itm/204358723277?
.. or RECOMMENDED -do it the proper way and and take the hub off and use a press - easy if you have all the adaptors with the press.
sorry cant help with brakes - others will.
all the best..mark