If Edward didn't kill James in Twilight why did Victoria spend all her time trying to kill Bella? In New Moon at the end Bella told Jacob herself she loved him so why in Eclipse did she deny it? Why didn't Edward sparkle in Breaking Dawn Part 1?

Edward wasn't the one to actually kill James,it was Jasper,Emmett and Alice that tore him to pieces and then burn him,while Edward was sucking the venom out of Bella when James bit her.Bella is the reason James was killed and Victoria thought since Edward was responsible for her mate being taken away from her that Edward should have his taken from him.
The answer to your secondo question,I think her Amore of Jacob is that of a very best friend and different than her Amore for Edward.Her feelings for Jacob weren't gonna change anything like she detto at the end of Eclipse.
Thirdly,Edward did sparkle very briefly in BD part 1 on their honeymoon te just missed it.