Probably you're going to have a really hard time in PK pre-parry. I can make it work, but I've also been trying a lot, lot longer.

An elf is going to feel extremely fragile at those levels, even compared to a human transmuter. You're down a fair amount of HP, iron weapons aren't all that rare even at very low levels, and you've got a 500 XP penalty making your range look a lot different.

Note that I'm not saying elf is a bad choice in the grander scheme of things, but as a lowbie mage it's not a small handicap. Your one saving grace is that when you wimpy away from someone beating your face in they'll have to either scan for which way you went or guess and hope, which often gives you the edge in escaping.

Getting some damage reduction out will help, but I don't know if it will help you enough. Stoneskin isn't a huge improvement over toughened skin, but if you're trying something dangerous enough it IS an improvement. Protection is pretty doable if you're attacking someone evil.

A mercenary of some kind is probably a help. Quicken it. Quicken yourself if you're going to be in a fight, for that matter. There are some cases in which you won't want to be but don't worry about that for now.

You should think twice about fighting anyone who can lag you until you get more comfortable with the class and what it can and can't do at those levels. Here's one place you see the XP penalty: a human or even half-elf transmuter at 15 will have few if any people in range with the Bash skill. As an elf transmuter at 15 I'm betting you have a lot of them.

As for what to lead with, it depends; I think meta slow is a pretty good opener when you're worried about melee damage, but if you're fighting, say, an invoker one on one it's probably a waste of rounds. I wouldn't even consider using bioluminescence except against the classes with hide or camouflage, and maybe not even then, depending on the terrain, conditions, and how confident you feel in your ability to be winning the fight.

Mental jolt is pretty solid at low-mid levels even just considering its damage; cloud and fire giants are vulnerable to it and will take additional damage, but most of them will also have Bash. (see above)

That's a pretty random set of responses. Hope it's helpful.