I like Chapter 9, it's a good place to grind for those chips that sell for a lot of money, meaning you get a nice stack of gil to purchase some more components that go towards levelling up your equipment. Though from experience, Chapter 11 is probably the best place if you want to stack up on that kind of stuff, so I think it's ok to just carry on as usual.
Yes you do change party members eventually

I was surprised that even at that point, with Snow in the team, you still couldn't switch members. Like the developers just wants you to play as Lightning/Fang/Hope even though it bears no real consequence to the story. I think you can switch in the next chapter.
I'm actually looking forward to hear your thoughts on the next chapter Ayako. I'm not saying anything, but I wonder if you will encounter the same difficulty I had when I came upon it. All I'll say is this. Be prepared!

Admist all this talk of future games to come, I totally forgot about an original FF game out now for the DS! It's Final Fantasy : The 4 Heroes of Light: