I played a hardcore blaster up to 41. That means once it died, the character was done. Understand what types of mitigation there are and how to use them. Yes, even knock back. My blaster was Eng/eng specifically for how much a bane it was to be on team. Hover works wonders in that regard. Using KB to knock mobs into a corner defaults to being super useful. I'm likely one of the fewer players who takes time to position themselves for attacks depending on what I want out of it versus merely hitting the most targets. There were times when near teams wipes happened when I decided to go off and helped preserve the team from further deaths. Understand aggro. A Fire blaster might sound awesome, but it will generate more heat than the blasts themselves.
The downside to /devices is set up time. I have seen blasters make for easy fights using devices, but it took time. Soloing would be easier for it. Teams which are blowing through content won't wait, but they won't really be needing it either.
Primaries I like. Dark and Ice are likely the most defensive. Ice being single target heavy means you won't draw that much attention to yourself. You get a hold. -speed and -recharge is nice. Dark has the -tohit and a heal. It also has KB. Dark is very DoT heavy, so you won't see huge numbers. Water is just a fun set which has some regen in an attack. Sonic can be good since it has -res in it, is single target focused, and has some controls. Don't underestimate using a sleep to help prevent a bad situation from getting worse, ie when a second mob gets aggroed. I used it on my Plant a bit on my last PUG. Who doesn't want an additional mob of Tsoo and their sorcerers coming into an already started fight? :)
If not /devices, I would double down on /ice and /dark for something to help ease the experience for a first time blaster.
I can't think of a must have for pool powers. Hover is nice. Hasten is nice. Med pool is nice, but honestly I would likely just jug greens. I just don't see them as being MUST HAVES.