Of the three powers you listed, I think frost breath is a keeper and the rest you should skip.
Here's a ranged soft cap (46% ranged defense), mostly ranged attacker build I put together. If you don't like fly, you can substitute super jump rather easily. The build doesn't have a lot of global recharge, but with soft capped range and aid self, you won't have a lot of down time with this build.
I went fire epic for the build only because char as a hold is excellent (and far outstrips bitter freeze ray) and stacks nicely with freeze ray. Bitter freeze ray does do more damage, but its horribly long animation is a major negative for me. I'd rather stack holds quickly and then use the other powers (which are all pretty fast, save frost breath) to take things down.
The other fire epic choices I took was the shield and rise of the phoenix. Soft capped ranged defense + resistance shield + aid self will mean you'll be fairly hard to take down. And in the event that they do, you have rise of the phoenix. 
This is a moderately expensive build but is far, far cheaper than the juiced up builds you see with lots of purples and lots of global recharge. I spec'ed my issue 2 ice/ice blaster somewhat similarly.
Note that fire sword is mostly used as a set mule, though it is slotted well enough to be serviceable. 
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
Click this DataLink to open the build!
Ice-Fire Blaster: Level 50 Science Blaster
Primary Power Set: Ice Blast
Secondary Power Set: Fire Manipulation
Power Pool: Flight
Power Pool: Fitness
Power Pool: Speed
Power Pool: Medicine
Ancillary Pool: Flame Mastery
Hero Profile:
Level 1: Ice Bolt -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(3), Thundr-Dmg/Rchg(13), Thundr-Acc/Dmg/Rchg(17), Thundr-Acc/Dmg/EndRdx(37), Thundr-Dmg/EndRdx/Rchg(43)
Level 1: Ring of Fire -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(15), Thundr-Dmg/Rchg(31), Thundr-Acc/Dmg/Rchg(39), Thundr-Acc/Dmg/EndRdx(46), Thundr-Dmg/EndRdx/Rchg(50)
Level 2: Ice Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(3), Thundr-Dmg/Rchg(5), Thundr-Acc/Dmg/Rchg(17), Thundr-Acc/Dmg/EndRdx(37), Thundr-Dmg/EndRdx/Rchg(40)
Level 4: Frost Breath -- Posi-Acc/Dmg(A), Posi-Dmg/EndRdx(5), Posi-Dmg/Rchg(7), Posi-Dmg/Rng(13), Posi-Acc/Dmg/EndRdx(34)
Level 6: Hover -- Zephyr-Travel(A), Zephyr-Travel/EndRdx(7)
Level 8: Freeze Ray -- Lock-Acc/Hold(A), Lock-Acc/Rchg(9), Lock-Rchg/Hold(9), Lock-EndRdx/Rchg/Hold(37), Lock-Acc/EndRdx/Rchg/Hold(43), Lock-%Hold(46)
Level 10: Fire Sword Circle -- Erad-Dmg/Rchg(A), Erad-Dmg(11), Erad-Acc/Dmg/Rchg(11), Sciroc-Acc/Dmg/EndRdx(34), Sciroc-Dmg/EndRdx(34)
Level 12: Swift -- Flight-I(A)
Level 14: Fly -- Zephyr-Travel(A), Zephyr-ResKB(15)
Level 16: Health -- Mrcl-Rcvry+(A)
Level 18: Bitter Ice Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(19), Thundr-Dmg/Rchg(19), Thundr-Dmg/EndRdx/Rchg(27), Thundr-Acc/Dmg/Rchg(29), Thundr-Acc/Dmg/EndRdx(29)
Level 20: Stamina -- EndMod-I(A), P'Shift-EndMod(21), P'Shift-End%(21)
Level 22: Build Up -- AdjTgt-Rchg(A), AdjTgt-ToHit/Rchg(23), RechRdx-I(23)
Level 24: Aim -- GSFC-ToHit(A), GSFC-ToHit/Rchg(25), GSFC-ToHit/Rchg/EndRdx(25), GSFC-Build%(31), GSFC-ToHit/EndRdx(33), GSFC-Rchg/EndRdx(40)
Level 26: Hasten -- RechRdx-I(A), RechRdx-I(27)
Level 28: Stimulant -- IntRdx-I(A)
Level 30: Aid Self -- Numna-Heal/EndRdx/Rchg(A), Numna-Heal/Rchg(31)
Level 32: Blizzard -- Dmg-I(A), Posi-Dmg/Rchg(33), Posi-Acc/Dmg(33)
Level 35: Ice Storm -- Posi-Dmg/EndRdx(A), Posi-Acc/Dmg(36), Posi-Dmg/Rchg(36), Posi-Acc/Dmg/EndRdx(36), Posi-Dmg/Rng(40)
Level 38: Fire Sword -- Mako-Acc/Dmg(A), Mako-Dmg/EndRdx(39), Mako-Dmg/Rchg(39), Mako-Acc/EndRdx/Rchg(43), Mako-Acc/Dmg/EndRdx/Rchg(45), Mako-Dam%(50)
Level 41: Char -- Lock-Acc/Hold(A), Lock-Acc/Rchg(42), Lock-Rchg/Hold(42), Lock-EndRdx/Rchg/Hold(42), Lock-Acc/EndRdx/Rchg/Hold(46), Lock-%Hold(48)
Level 44: Fire Shield -- S'fstPrt-ResDam/EndRdx(A), S'fstPrt-ResDam/Def+(45), ResDam-I(45)
Level 47: Rise of the Phoenix -- Erad-Dmg/Rchg(A), Erad-Acc/Rchg(48), Erad-Acc/Dmg/Rchg(48)
Level 49: Super Speed -- Zephyr-Travel/EndRdx(A), Zephyr-ResKB(50)
------------
Level 1: Brawl -- Acc-I(A)
Level 1: Sprint -- ULeap-Stlth(A)
Level 2: Rest -- RechRdx-I(A)
Level 1: Defiance
------------
Set Bonus Totals:
- 13.5% DamageBuff(Smashing)
- 13.5% DamageBuff(Lethal)
- 13.5% DamageBuff(Fire)
- 13.5% DamageBuff(Cold)
- 13.5% DamageBuff(Energy)
- 13.5% DamageBuff(Negative)
- 13.5% DamageBuff(Toxic)
- 13.5% DamageBuff(Psionic)
- 4.25% Defense(Smashing)
- 4.25% Defense(Lethal)
- 6.75% Defense(Fire)
- 6.75% Defense(Cold)
- 35.8% Defense(Energy)
- 35.8% Defense(Negative)
- 3% Defense(Psionic)
- 5.5% Defense(Melee)
- 44.3% Defense(Ranged)
- 10.5% Defense(AoE)
- 3.6% Max End
- 46% Enhancement(Accuracy)
- 12.5% Enhancement(RechargeTime)
- 5% Enhancement(Held)
- 26% FlySpeed
- 40.7 HP (3.37%) HitPoints
- 26% JumpHeight
- 26% JumpSpeed
- Knockback (Mag -8)
- Knockup (Mag -8)
- MezResist(Held) 7.7%
- MezResist(Immobilize) 3.3%
- 19.5% (0.33 End/sec) Recovery
- 22% (1.11 HP/sec) Regeneration
- 3.15% Resistance(Fire)
- 3.15% Resistance(Cold)
- 26% RunSpeed
Code:
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Its was my first hero, made when i bought the game (2006..)
Now she needs a respec to get sets (she's still using SO) and im not sure about some powers...
She has Hot feet (picked up just because it looks cool, but not very good on a blaster :/) and i was thinking to change it for Ice breath or Bitter Freeze ray; what do you think?
Those 3 powers arent very usefull... but sets can give them some utility
What should i pick?
Any other suggetsion?