One question. I looked at the algorithm and it seems that you'll get paid extra credit even if you stopped mining. Is it right?
Yes. I answered this in the post immediately above yours!
If it is so, is there a variant that miners that ceased their activity (did not submitted share for given round) will be paid last?
Recent Shared Maximum Pay Per Share. (I mentioned this in that last post too...)
Also, isn't this problem in ESMPPS? The veteran miners might be motivated to mine under new address to get paid sooner.
Using a new address doesn't have any influence on ESMPPS. The equalization is per-share, not per-address.