New player looking for some build advice

So I started this game not too long ago, tried to pull hiyuki accidentally pulled the wrong banner. Happy accident tho I like her character but I’m not too sure how to build her and if I should bit the bullet of using synthesize for upgrade materials or power through to the third chapter, I’m just barely starting the second though and I have no idea how long this will take?

Complete side note but do character from older versions like chapter one and two still get consistent reruns? I’m asking because I saw someone say last banner might of been chisa’s last rerun

And thank you for everyone kind enough to answer