No, you will not have to "fully believe" in them. They will likely mention them, and probably recommend reading both the small and large catechism. However, the ELCA does not require their adherence to be a member.
Most require new members to go through a new member class of some sort. Mine was 5 weeks long, 1 hour each week after the service. It was really basic information on the history of our parish, the ELCA, basic Christian doctrine, basic Lutheran doctrine, and how the church functions.
Teaching was both via material and question/answer. It was mostly led by the pastor, but they also had other church leaders present and talk.
All that said, the Eucharist is a pretty foundational part of Lutheran doctrine, even in the ELCA. The understanding is more than a Spiritual presence. You may want to investigate the Episcopal or Methodist churches if you lean that way but still want s church that is similar to the ELCA in liturgical practice.
What draws you to the ELCA?