I have just realised that I didn't answer your question. I'm sorry for the omission.
The equivalent service to the RC Mass is the Divine Liturgy. It has a somewhat different shape to the Mass, although the essential elements are present. It also takes longer. The Liturgy of St James takes about two hours. The liturgies used are of great antiquity, tracing back to the very earliest days of the Church, and have suffered little change except for translation. The normal attitude for prayer is standing, without shoes, although there are brief prostrations. Commonly the Divine Liturgy is prefixed by the "Raising of Incense", which is a very formalised Morning Prayer (and also Evening Prayer, too). It takes about an hour to an hour and a half. Thus on Sunday mornings we will be worshipping for perhaps up to three hours or so. Such length of service is characteristic of Orthodoxy.
You mention the matter of "inter-communion" as it is sometimes called. Certainly the consecrated species is restricted to baptised Orthodox. In a way, this makes it even more special when eventually you are granted Communion after prayer, studies and Baptism. However, the Divine Liturgy includes another, to me very meaningful, element. Early in the service the priest examines a number of loaves that have been baked specially for the occasion. He choses one for consecration, and the remainder are blessed and put aside. At the end of the Liturgy this blessed bread is distributed to all present, (including non-Orthodox) known as the Antidoran. Clearly this is a sharing of bread blessed by God which brings us all together.
I hope these notes are helpful.
With love and prayers,