4 is entirely possible, J20 flies just fine with 4 2400L drop tanks installed. It doesn't even interfere with the IWB air to air missile carrying, but range might get reduced by quite a bit.
The smaller PL-XX seems to have the same length as PL-15. Its just much thicker. I wonder if J-20 IWB is capable of carrying these. If they have sufficient depth, they should be able to carry atleast 2 internally and possibly 4.
Only PL-15 is correct. The rest is pure speculation, meaningless.
I have doubts about PL-15. On May 7th, PAF killed IAF aircraft using PL-15s that included at least one kill with an extremely long range of ~190 KM. How did they do it when the head-on range is 180 km?
That's how the russian do it, short and fat. So far they are the only ones with operation bay-combatible VLRAAMs. I'm sure at least theoretically the J-36 could fit a fatter PL-17 like missile with 1000km range in it's larger bays. While the other 5th and 6th gen could fit a fatter PL-15 like missile with say 600km or so range, which is still a great increase over current types. Considering that bay compatible VLRAAMs are the next need to have for the major powers, hopefully China is already working on this/testing hardware.