haven't played it for so long so i can't remember much, anyway i'll try to help
first of all, i think one of your GF, probably diablo has an ability to keep you from running in monster, don't remember what is was though but yous should be able to find it. if the thing doesn't work down there then the only way is to fight.... i'm not sure but i think i was able to run away cos i never had any trouble fighting with monster when i played, i was pretty much in control of whom i wanna fight with. but if the thing doesn't work then you jsut gotta fight yourself..... use a lot of GF (good thing about ff8 is that you don't have to wait for the gf get beaten up to use the overdrive and you can always revive your Gf after the battle so you shouldn't ahve any trouble with that. after get to eden, if you have siren's ability to find, you probably can find the saving point, if you don't it's just right next to the machine (as far as i remember, you gotta search some kinda machine thing to get eden appear, the save point is just right next to it, keep pressing x around the place, you should be able to find it.)
what else? oh, when you fight eden, the beast has some really nasty attack so you wanna make sure that you hero (get 100 heroes from one of the character cards, not sure which one )if you have the guide book, they probably tell you to convert the hero into 10 other thingy, don't do that just keep them as heroes, you should be find. use heros on your character to keep them invisible..... the smartest character choice in for the battle should be squall, rinoa, and zell ( zell is optional ) but you definitely need squall for the limit break and riona for her doggie, the dog is very useful in the battle, make sure you have squall and riona use limit break a lot by casting auron on them. bye the way, don't forget to cast the spell on them before using heros otherwise, it'll be in vain. one more thing, use heros wisely, you still need them for fight omega and the final boss, make sure you don't use more than 30 heroes. (i myself used somewhere like 40 or more cos waste them on other non boss monster that's why i didn't fight omega) well, i guess that's all you should be fine with the strategy.... good luck