Ps4 – If someone makes a profile on the console can they use the sub on their console too

No. Content licenses are bound to the account that activated them. Once the PSN+ account laps, it defaults to a standard PSN account, the free games that were licensed would then be invalid on that system for all accounts. But, any games you had actually purchased, even at a discount price would still be available for all accounts (unless you also removed the account from the system).

The only way to be able to play those games again would be to either renew your subscription to the account that originally downloaded them, or just buy them under the alternate account.

Specifically in regards to your question though. Any "free" games that you downloaded on your UK profile would have to be re-purchased by the US profile to re-aquire them. The only way you would be able to have them free for the US profile is if you had also had a paid US account concurrent to your UK account and had activated the game when (or if) it had been available for that account.

I know you may think this is stupid but remember, the free games are a perk for paid subscribers for that region. If you no longer subscribe to that region then you are no longer eligible for the perks.

According to this site, you are able to do what you described for you and your friend to share games. However, in order to play your own games, you will be required to have an active connection to the internet at all times, which is less than ideal.

However, because your own PS4 will not be registered as your primary PS4, no one besides you can access your games on your PS4. However, everyone who has access to your console will be able to play your friend's games, since that would be the account with your PS4 listed as its primary. Likewise, anyone that plays on your friend's PS4 could access games that you have purchased on your account.

Savefiles are kept on a per-account basis, so any games that your brother plays on his account will not affect you or your friend's savefiles in any way.