Do anda Think Darth Vader Loved Leia sejak the time he died? and another soalan as well.

I think he probably did; he mentions her in his dying moments and asks Luke to tell her that he became good again which suggests that, even though he never interacted with her knowing he was her father, he wants her to know that he was able to do good.
As to the saat question, it's mentioned in the third film that Qui-Gon had learnt to come back and it's implied that he taught Obi-Wan and Yoda (not sure how Anakin managed, possibly on his own like Qui-Gon did atau maybe he was taught as well, it's never said) to do the same. I don't think people who aren't Jedi atau Sith can come back in that way, which is why Padme and a lot of others didn't come back.

Of course he loved Leia (l checked wookiepedia)
Padme didn't appeare as a ghost 'cause..well, first resson is
-She's not a jedi
-And only Jedis atau Siths who learned how to appeare as a ghosts (like in Revenge of the Sith at the end when Yoda asked Obi-Wan to go to Tatooine, there he will learn about spirit's world sejak Qui-Gon Jinn)

1. I think he did.
2. Padme wasn't a Jedi.

I think he did Cinta her, after all she is his daughter. I know he loved Luke. His son helped turn him back to the good side. Padme wasn't a Jedi and I don't think she could appear as a Force spirit.

Of course he loved Leia he told Luke to tell her he was right about him