depends on many things.
many orthodox churches will accept protestant baptism (from a mainstream protestant church) if it is done in a trinitarian fashion, and especially if it is done by immersion.
others will not.
if they want you to be baptised again, and if you believe that your first baptism was valid; then consider that the orthodox baptism is a completion of the process that was started all those years ago.
either way, you will need to be chrismated (like confirmation). this is something very beautiful and i am sure it will be unlike anything you experienced before.
as for confession, this is something we all need to do regularly (once a week to once a year, depending on each person and on the church; i think the average is about once a month) and it is like going to see a spiritual sort of 'family doctor'.
to give an example from once of my confessions: priest says 'how's it going?'; i say 'i have been a bit down lately and stressed'; priest asks 'how is your spiritual life?'; i say 'wow, you seem to know i have not been praying so much lately!'; priest gives me personalised advice on how to improve my spiritual life, then i mention other things i have not been doing so well lately and explain that i pray for strength from God to do better. then the priest prays for me and puts the cross on my head and we say together 'our Father in heaven, hallowed be Your name etc.' then i feel much better and exchange big smiles with the priest, and then i go off and have a cup of tea with my friends and someone else goes for confession. (don't worry we make sure the priest gets his cup of tea too!)
before chrismation, sometimes you need to do a longer confession, where you have a chat with the priest and ask him to pray to God on your behalf for the wrong things you have done in your life. in my case, i had been to confession several times before chrismation, but this was not common. either way, it is something beautiful, not something horrible.
maybe before confession you will cry when you tell God you repent, but after that it is beautiful.
God is merciful to forgive, and it is a big load off your chest when you have confessed.