Heh. He's far from being the worst male main character... Maybe you are lucky if you haven't seen worse. I could name a few, but that would probably earn me negative reputation, so I'll leave it at that. In fact, I don't even think he's that bad. He has developed somewhat during the series. Plus he managed to kiss Saber, which is more than great many male characters ever achieve...

I have no idea if Saber stays or not. Since this is from the same maker as Shingetsutan Tsukihime, I almost think she vanishes at the end, and Shiro is left with only memories of a lost love.