Effectual prayer is prayer that produces results. Results come from speaking in faith.
Fervent prayer is prayer that issues from your HeartFaith, from a place of compassion and earnestness.
We are instructed here to pray one for another. This is speaking about the body of Christ and members praying for other members.
We are not to pray for unbelievers without first presenting the healer to them. We are to witness to unbelievers so that they become believers and then we pray for their other needs.
If a person rejects Christ Jesus they are to suffer the consequences of their sin. Don`t ask the Lord to violate His Word.
Remember, it was Jesus` teaching that produced faith for the healings that followed.
In the first part of this verse James is not talking about airing dirty laundry.
We are to confess our offense to the person we offended.