I think typically, non-paedeobaptists can join PCA churches if they vow to submit to the authority and to promote the purity and peace of the church. In other words, I wouldn't join a PCA church being a baptist and try to convert them over to being credo. We have many baptist folks in our church, who are members. They submit to the teaching on baptism, although they aren't in agreement. The other day we had a believer's baptism and it was wonderful.
Yes.
Studying the "peace and purity" vow relats to peaceably studying the doctrine of the church (which is its unity).
Since infant baptisms are performed as ordinances of the church in the ordinary course of corporate worship, someone with a strong conviction otherwise is going to have difficulty maintaining their submission. Add to that, part of the ordinance is the congregation taking vows to receive and help the infant be raised in community in the nurture and admonition of the Lord.
Consistent with a church "confessing" doctrine, and it being the basis of her unity, I would not set an expectation that someone who is a confirmed believer's only baptism can join and remain so with no intention to reconsider. For example, that person could not become an officer, ever. They could not teach or promote that doctrine.
So, realistically, at minimum, the person needs to be open to considering and earnestly so, the confessed doctrine of the church.
And you are right- it is often not noted, PCA churches do believer's baptism also. So on a given Lord's Day, one could see both an infant baptised based on the covenant promises and faith of the parents, as well as an adult by profession.
And, you are right again- it is beautiful!
