Questions regarding Crystals and Gems

[Bahamut ZERO]

My mother's been playing T3 off of PSP, which is great because she's been jonesin' for some Zelda action for quite some time. I've been helping her play through it (looking for things when she gets frustrated with it, or with dungeons etc), but we've come to a point where we are stuck, and after trolling around the topics here I have a few questions that i hope you fine people can help with.

1: Where are crystals #2 and #7? From other posts I've read you find #7 after the other 6 are found, but #2 eludes us. Only place I could figure #2 might be would be in the desert, as I can see a fence on an unreachable cliff in the southern section, but can't for the life for me reach it

2: That temple that you need all 200 power gems.... is it a requirement for beating the game, or is it optional? I think I'm close to having them all anyways, as the 40 gem defense boost is the only thing left in the shop (we have 22 so far! ) BUT if it's optional that would make things go a lot more smoothly.

Here's hoping you guys can offer us some wisdom! Thank you guys very much for making this awesome trilogy, and for Spike (think that's his name?) for porting it to PSP (I still need to get the update to do the casino lol). Also, I can't wait to see Navi's Quest hit 1.5 so it'll be ported to PSP as well. I don't have my own comp at the moment, or else I'd download that badboy right now and try it out!

EDIT: Just realized Navi's Quest has already been ported, so here in a bit when I'm near wifi I'll be getting ahold of it ASAP.