Anglican, so I believe in the Real (physical and spiritual) Presence of Christ in Holy Communion.
When does He become Present? I don't know and it doesn't matter, although logically He is there by the Great Amen.
How exactly does He become Present? I don't know and it doesn't matter, although, again, He is both physically and spiritually there (no half persons; He is either really there or He isn't)
Is there anything of bread and wine with water left? I don't know and it doesn't matter, only that I receive Jesus the Christ each time.
I suppose you could say my Eucharistic theology solely on the "Objective Reality," that is, that Jesus is truly, wholly, really there. Any particulars outside of that don't matter, only that He is there as He Himself taught.