\\I don't know if I can remain Eastern Catholic if Eastern Catholics don't believe in the Immaculate Conception, Infallibility of the Pope, Purgatory, etc, because I believe those things...\\

These things are, from the Eastern point of view, non-issues.

They certainly have nothing to do with the way I live my spiritual life.

Do you really want to know what the Eastern Catholic Churches, especially the Byzantine Churches believe on these matters? Look up the teachings in the appropriate liturgical books, especially for 9 December and the Saturday of the Souls.

I have nothing to add to what is written there.