I've never used soy wax, but I've heard it's much softer compared to candelilla wax. Candelilla is so hard that you can use half the amount of it that you would normally use of beeswax in your formula, which leaves extra room to add more oils and butters in your formula.
I've only been making balms for about 3 weeks or so now, but I have candelilla wax, carnauba wax (another vegan wax), and beeswax on hand and I've been playing around and making lots of different balms with them. It's getting to be as addicting as soapmaking is for me!
Anyway, I've used candelilla alone and also in combination with carnauba wax, and so far I really like how my lip balms have turned out. I've noticed that besides being super hard, the candelilla also leaves a nice glossy sheen behind on the lips. Oh, by the way, carnauba wax is also super hard like candelilla wax.
As for your second question......well, that's a good question!
On the MMS website, I found a guideline on how to formulate your own lip balms:
* 20% Beeswax
* 25% solid at room temperature oil (Coconut Oil, Palm Oil, Shea Butter, Lanolin, etc.)
* 15% brittle at room temperature oil (Regular Cocoa Butter, Palm Kernel Oil, etc.)
* 40% liquid oil at room temperature (Sweet Almond Oil, Olive Oil, Avocado Oil, etc.)
If I was going to use hemp butter in my lip balm formula, I'm thinking that I would figure it into my 'solid at room temp oil' portion.
HTH
IrishLass