Answer #1:
put it on the person's character portrait. they should resurrect when the rose animation finishes. You can buy rods in various stores (Ribald) or get one off Mekrath's corpse.
Answer #2:
i always use the Daystar from the Crooked Crane. just get someone who can use it (minsc, yoshi, nalia) to stand next to where he spawns. when the dude is about to rise up (undead animation at the "elbows-out" stage, get them to cast Sunray. if you time it right and get lucky, he'll get toasted before he can mirror image himself. it takes a while, but can be accomplished by low-level parties easily.
Answer #3:
not really a question, but if you have the bonus merchants, buy the Shield of Balduran from Diedre. it reflects beholder rays. if you don't have ToB, the Cloak of Mirroring works too. I'm still working on the Cloak of Non-Detection fix, though. Otherwise, they make really tough opponents. i assume a party member got killed by the highly unfair Death Ray. unless you download the
Baldurdash patch, it bypasses everything, including MR and even a Protection from Magic scroll. good luck.