What is your playstyle going to be?
1) Do not invest in Strength, unlock Arcane Warrior, take Combat Magic and then your Magic Score
will act as your STR score in regards to items and Damage.
Take it as your first specialization so you can wield your weapons and armor at about LVL7.
If you go BM, spend points on Magic and Constitution evenly, I would suggest trying and finding your playstyle.
Favor Magic until you an wear the armor and sword you want, then favour CON until you are comfortable with it.
I play a pure AW so I cannot help with Bloodmage exactly, but I would suggest
an about even Ratio.
2. Kudos for sticking to some RP-reasoning in choosing your spells xD
Apart from the Fire-Line?
Do not forget sustained spells. For a dark feeling, pick up Miasma, its a great debuff and will
greatly help you with hitting and avoiding stuff, also slowing mobs around you.
I myself am a strong supporter of +def, so pick up Arcane Shield, too.
If you want UBER-Damage, pick up Spell Might and cast it before you fire off your big damage spells for larger numbers. Granted, it will somewhat reduce your offensive flexibility, but since
you will not take any ICE spells, you might just as well use your points for a super-powered-up
fireball or Inferno.
Also: Pick up Mana-Clash too, pair it up with Spell Might and watch Enemy Casters implode at your evil warlock's whim xD. They just...disappear....<_<
3. It's very playable, especially due to the AW/BM insaneness.
Just be careful that you can go solo if need be, as the game forces you to solo sometime in the Fade as you try to take down the Sloth Demon (since this is the SPOILER forum, I figured its safe to say...)
Also be careful about Trolls or Dragons that like to pick and grab you, but with you being a BloodMage and your +con, you should survive
As with Starfang, I would suggest as much Dweomer or Hale, as you can get, since +Spell Resistance will protect you from the big and small nukes better, same with Physical Damage.
If you get hit for 1 less damage 1000 times, you have prevented 1000 Damage...
You are always welcome xD - I hope I helped
If you want to get bloody and dirty, I would dearly suggest Haste, either pick it up yourself or have someone cast it. (If you don't wannt to pick it up, take Wynne for the Wynne)