Knaidlach,
1. I find it hard to believe that Rav Eliashiv said “machnissei harachamim”.He was a Litvak and the Gra even opposed “barchunei l’shalom”. In any case, what does that have to do with the dead (BTW, the Gra opposed going to cemeteries in general as do the Briskers)?
2. If you are referring to Rav Kook’s teshuva on leaving EY to go to kivrei tzaddikim,he odes not say that it is a chumra but ikar hadin. He also says that it is not clear that there is a mitzva at all.
3. Rav Tuchachinsky casts doubts on the practice of making requests of the dead (Gesher haChaim 2:25). Certainly actually davening to them is a”z.