Help With Building a Light/Cold Sorc
So, after becoming rather disappointed with my Blizzard sorc (she's great at nightmare anything, but fails at most Act3 and on areas in Hell) I decided to make a dual element sorc, so I can at least have a reliable backup spell for when I hit mobs immune to Lightning (my main element)
For the point distribution, I was thinking:
20 Charged Bold
20 Lightning
20 Chain Lightning
1 Static Field
1 Telekinesis
1 Teleport
20 Frozen Orb (+5 pts from the prereqs)
1 Warmth
1 Lightning Mastery (along with all spare points)
Total: 90 points. With the points from the skill quests (Akara, Radament and Tyrael), it can be finished by level 78, unless I made a mistake somewhere, which is likely.
Now, to what I need help with. Order of maxing stuff. At what point should I have Frozen Orb do decent damage? Lightning Immunes don't show up until ActIV / Act V Nightmare, iirc, and by that time I should be level 60-ish. Should I start working on Frozen Orb after killing NM Diablo? Or earlier than that? I don't want to have to scrub another character because of immune problems.
At one point I will hopefully get an Infinity, but I can't count on that, as I'm rather free with stuff I don't use/need so I don't think I'll afford one in a hurry. So don't suggest I get one

I'm aware that it exists, and I'll be using my Blizzard sorc to try to get one, it'll just take me a loooong time.
As far as attributes go, I'll go for enough str for Spirit, with the rest in Vit. It works very well for my Blizzard sorc, so I see no reason to change it.
Gear suggestions are welcome too.
Thanks in advance.
Oh, and I won't be MFing much with her, just killing stuff. It's why I hate all the cold immunes. I like killing stuff, not getting to a specific monster, dropping it and repeating that over and over.