i'm playing it, just got my 5th character. i like it so far (karin

), but i got some questions:
1. i can get new elemental forms in the graveyard or enhance the ones i already have. does it pay to strengthen the weaker forms? and do i get more attacks for the current or later forms if i enhance them?
2. are most sidequests skippable? it seems each character needs some items to develop their abilities too, and there are already quite a few spots on the map, so i'm wondering if i'll need a guide to get those.
3. how long is this game?
4. will the battles be challenging later on? 'cause so far it's been easier than ffx. ;/
5. is something in this game not explained because it's a sequel, like yuri's relationship with the little girl?
tia