Hello,
I am so sorry to hear you are faced with these issues. It does highlight how cats can 'act out' when circumstances change
Firstly, photos always help. People do love to see pictures. Are they brown/snow/silver, spotted/marble etc. Also, are they registered and do you have their papers? If they are registered, have you considered letting the breeder know as they may be able to help you rehome them?? Do they have to/need to go together? Is the girl fed up of the boy???
Whilst they are still with you there may be a few things you can do to help the problems.
Your boy seems to be the main culprit (typical man!). Have you had him checked out with a vet regarding the wee'ing? It more than likely is behavioral but it could possibly be a urine infection of cystitis. You may not have the room but could you place a few more litter trays around so he is never too far away. Try not to get mad at him for wee'ing as he won't understand why, don't shout, or rub his nose in it etc (you probably aren't doing it but it's worth mentioning). Try to place him on the tray every now and then and dig with a paw, don't force the issue though. Praise him when he does wee on the tray, maybe with treats. Make sure you clean urine with an enzymatic cleaner such as Urine Off and follow instructions on bottle.
He may benefit from a natural medicine called Zylkene. It can be used to help calm down stressed cats. I buy mine from VetsUk usually. He may also benefit from prescribable medication to calm him but i would try Zylkene first.
I hope this helps you a little. You may have guessed but i have a stressy Bengal who wee's on stuff!!!!!
Unfortunately, i cannot help with the rehome so i wish you lots of luck.