I was wondering are they worth killing? , and what equipment should I bring if I do fight them, because I was thinking about buying karils.

Just buy Black D Hide, and some kind of bow and use the wall safespots. ghey are shown in a guide made by Axe Man Jack in the AoW

Bloodvelds are great Slayer XP, but I wouldn' consider them a good training monster. Basically they drop Blood Runes and Rune Meds. If you really want to train on them, I would recommend Bones to Peaches with Black D Hides.

Yeah, you can range them safely but it is faster to melee. Either way wear black dragonhide armor. The drops are not particularly good though. You can get more money killing banshees or basilisks.