You don't qualify for Rent Supplement while you're living at home. You may be entitled if you move to a rented property, there are different rent limits depending on where you will be living, and your wages would be assessed so it's difficult to say how much you might be entitled to.
Your one parent family payment will be reduced if you earn over 146 euro per week. It will be reduced by 1 euro for every 2 euro you earn above this amount. If you earn less than 146 euro, your OPFP payment isn't affected.