There isn't really a hard class to play. My two mains are a 50 sniper and 50 scoundrel and they're not hard to play at all. In PvP, I can take down someone with my sniper(not even full BM) in 4-5 shots without heals while scoundrel healing is really simple with only a few heals available. Once you choose an advanced class and get used to the play style of the class then there shouldn't be any problems.
Am I the only one who hasn't had any trouble with this? I cleared this with my scoundrel, sniper, and juggernaut all at lvl 47. Pop all your cooldowns, get your best companion out, use heroic moment, use medpacs and you'll be fine.
I've been looking at these videos and I really like the chest piece that the warrior was wearing but I have never seen it in game so does it exist?
Skip to 1:57 in the progression video.
I loved my nemesis in the agent chapter 3. It was a battle of wits and I really enjoyed it especially the ending, I couldn't ask for a better rival as that one was the best.
I thought I was the only one to notice this. It's a really subtle change and I did notice it. My agent seemed to transform from a cheerful novice to a broken down veteran.