Others have already written the best answers, but I do want to say that I can empathize with you in regards to returning to the RCC. As a former Catholic, myself. The draw to return to the church that claims to have all the answers, and claims that with authority is strong.
Even when one knows or believes their theology or practices to be flawed, the pull is strong. There is a comfort in a church that has all their beliefs lined up, all of them written in the Catechism. But then, comfort is not necessarily where Truth is found.
Continue your study and asking questions here and in other places. Reach out to your pastor, and other Lutheran pastors if need be. The Lutheran church has a rich history and body of teachings to pull from, generally your questions can be answered, but it may take some searching.