You can say tehilim from Perek 119 using the specific letters to spell out the first and middle name of the person. Also, in the Artscroll “Mourning in Halacha” book, there are specific tefilos to say for a parent. I also read that you are not supposed to ask the deceased for anything, so I just ask HaShem to take care of them and tell them I miss them :(.
A Maimonedian-based rationalist would probably tell you remember their lives and use it as an inspiration to do better or to take on something new for yourself. A Chassidish-based/Kabbalistic-oriented person would tell you do daven in their Zechus or that they attempt to intercede with Hashem on your behalf.
why not? at every levaya the speakers ask that the niftar should be a mailetz yosher for the family AND FOR KLAL YISROEL. unless you don’t fall into one of those categories, i assume that is the case. just be careful not to daven TO the person.
good question, dg. probably bc at said levayas, assuming that nature has taken its natural course and the children outlive the parents, people do say the parent should be a mailetz yosher for the children. a sort of nechama for the children.