If the enhanced powers of parliament weren't used before to shuffle things around they won't be used after. There were no powers to shuffle things around that parliament didn't already have.
No that is a fundamental misunderstanding of British law and Parliamentary tradition. Entities could not use courts and EU law to overturn acts of parliaments. The most they could do is tell parliament that they are in breach of EU law and so must decide what to do but it is impossible for a court to overturn an act of parliament. The UK parliament is and always has been completely sovereign. Even UK courts can't overturn an act of parliament. The UK isn't like the US where we have a written constitution where all laws need to conform to it. The times that the EU could affect UK law was when parliament had specifically legislated for the EU to have those powers. Even in those cases though it was an act of parliament that gave those powers.
The closest argument you could make is that if the UK still didn't want to follow EU law when it was in breach then it'd have to make a decision of paying fines (because it'd legislated to give the EU to right to fine it) or leave the EU.
