I did the caves at 75 defence aswell I just attacked them all once and lined em up. Then turn on steel skin prayer, didnt have to use any sara brew dose at all in the fight with Jad.
You'll keep the c bow, a guide on another runescape fansite tells that the c bow has undetermined value ( if its true the cbow protects over d chain). The crystal bow cannot be alched or sold to a store so i think you'll always keep it unless you're skulled
For Crystal seed recharging you have to go to Ilfeen (try the map at the main site) She is near the middle of the map. Islwyn sells the bows and shields, but those prices are always the same. He is either at the east or west side