It's not set in stone that they have to have played. I thought that was the case, but it turns out there's actually quite a lot of leeway with it.
Believe McLoughlin is on a longer term deal than what Transfer Markt says - maybe 2024? With an option? edit - https://www.hullcitytigers.com/news/2021/march/sean-mcloughlin-new-deal/
Basically, this: New Work Permit Requirements For Players Moving To English Clubs Post-Brexit (worldfootballindex.com)
No, but there's an appeals process that can determine if the player would be of value to the club (it's basically to stop bigger clubs abusing smaller, foreign ones for young players). For example, the target player is the captain of his team and he's featured regularly for the past two seasons (though he's only played a few times this season due to injury/suspension). I don't think he'd be a genuine target if they didn't think he would be allowed to come.
I would hope if players are out of contract come the end of the season, any new ownership team would already be drawing up a list of players they want to retain, and sitting down with them in the first few weeks post-takeover to organise new contracts before the January window opens, or in the first few weeks. That way they have a clear idea of where they stand with the squad before any outgoings.
Well it's been interesting a little bit, but time for cuppa and a movie i think. Sorry i went off topic,