After inflation ended, did the expansion slow down to non-inflationary expansion because of gravity? Assuming that inflation occurred, it accelerated from the previous expansion to inflationary expansion.
After inflation ended, did the inflationary expansion instantly change into the previous expansion rate before inflation occured, or did the inflationary expansion gradually decelerate due to gravity?
 A: There is no instantaneous change in the expansion rate. As inflation ends, the expansion smoothly changes from being exponential back to being a power law. But this is not because attractive gravity is slowing the expansion; it is because the repulsive gravity produced by dark energy, which is driving the exponential expansion, diminishes as the dark energy is transformed into matter. Of course, all this happens in something like 10^-32 seconds!
A: If we talk about repelling gravity we have to consider the inflaton field during inflation  and the cosmological constant much later. Both are independent of each other and cause the universe to expand exponentially in the absence of attractive gravity due to radiation and matter.
At the end of inflation the inflaton field decays into matter. Thus the exponential expansion turnes to decelerated expansion then. The reason is that now the energy density of the universe is dominated by radiation and matter because the inflaton is finished and the density of the cosmological constant (people talk about dark energy, the data are consistent with the cc though) is negligible. It will become important though and responsible for the accelerated expansion we observe today only billions of years later when the matter density has been decreasing significanty due to expansion whereas the cc is constant over time.  
