I've been practising my hill starts on my CBR 600 F4 and noticed that the bike does not pull very well when I take off in 1st gear, then it suddenly rockets when it hits about 3000 rpm. Is this normal?

I know my chain needs replacing soon, so I'm not sure if these events are related at all.

Another thing is I noticed a slight vibration around 6000rpm when doing around 80 km/h in 3rd (I think). I heard this can be the cam chain tensioner going, or is this perfectly normal? It's not really too bad and does go away if I accelerate or decelerate.