How is exactly a repo functionning?

When I enter in a reverse repo, I give C1 cash at t1 against a bond/asset. At t2 I'll return the bond and get C2>=C1 (GMA).
Is the next structure correct?

Before the repo:
BS:
Assets=Cash=C1
(Liabilities=Equity=C1)

During the repo:

BS:
Assets: Claim C(t)=C1*(1+R(t2-t)), with R=(C2-C1)/(t2-t1)=repo rate
(Liabilities=Equity=C(t))
Off BS:bond-MV(t)

Where is the margining entering? Say it is cash.

And what is the (net) present value of the bond I have been transffered, at moment t? (in practice, it's present value is C2)

Hope that somebody could help