Re: Newbie thoughts - think back your early years - what comes to your mind?
I wouldn't give up moderate weight training, aikido really doesn't work your muscle groups and you don't want to lose tone. Of course I am a tiny 51 year old woman who uses low weights & high reps...Flexibility is also debatable-no one in my dojo but me can touch their toes without bending their knees. Rolling practice alone should give your back the flexibility it needs to do ukemi, however I am all for combining yoga with aikido.
Oh, at 2nd kyu I"m still very much in my newbie years. One thing I've loved was maturing from beng the "baby" in the class and resenting new students who "stole attention away from me" to being the first to welcome any new visitor or prospsctive dojo member with sincere enthusiasm.
And yeah, one of my favorite training partners is built like a ton of bricks.