I'm level 34 now, and quite honestly I've still not really delved into the whole profile thing. It's taken me this long to max out my three favourite skills as a vanguard (singularity, charge and nova) plus some of the passive lines, for shotguns, health and shields etc. Also, found out that when you switch profiles all your new skills immediately go into cooldown, which is there I guess to stop you abusing it, but at the same time it means it's not as reactive in the heat of combat as I thought it would be.
Do you mean the AI Peebee creates? It opens up a new ability, which looks like it could be fun, but again I've not put any points into it. After I've maxed out these skills I'll probably start working on an infiltrator/sniper profile a bit, for fights where you want to keep a bit of distance. But to be honest I've not really felt a huge need for that as yet.
Yep, am enjoying it a lot as well. The companions really grow on you as well the more you speak to them and move through the story together. They're not as in-your-face as some Bioware NPCs and a bit more nuanced perhaps than some of their usual archetypes. Having spent a good amount of time with them now I don't think there's a weak one really, although I find Peebee vaguely annoying a lot of the time.
My face is tired.