Endura from 2009 will be fine. I've used stuff much older than that with fine results. It is somewhat scarce though I still keep finding it.
10L of RA-4 should do at least 500 8x10s. Probably more. I am on my first batch of 10L that I am keeping track of, and am about 7L down, with several hundred 8x10 and 8.5x11 prints made. I turned down the replenishment quite a bit and it still processes great. (CP-31).