I'm only familiar with the Catechism of St Philaret of Moscow. I'd recommend that one to you.
I'm not sure how far along you are in your journey and I don't want to confuse or discourage you. Are you familiar with Ecumenism? This is a heresy that, unfortunately, ROCOR has embraced through its union with the Moscow Patriarchate. True Orthodox ( this is a True Orthodox forum, after all) believe that those who knowingly embrace Ecumenism are under anathema. Therefore, ROCOR is not a recommended jurisdiction.