Flat side of head:
My baby also had that on her right side. Then we changed her sleeping position in the cot from 3rd month onwards so that her left side is facing out, and right side is facing the wall. Her head is rounder now. Our PD didn't say anything about it leh..
Cradle cap:
My baby had it on her eyebrows and a bit on the head. We used Johnson's baby oil about 30minutes before bath, and wipe it away. During bath we wipe eyebrow away with clear water too. The crust were quite persistent, but went away after about 2 weeks. Actually, if you search online, it was said that rubbing breastmilk on the crust consistently can make the crust go away..
Bumbo seat:
I just bought my yellow one from a fellow mummy for $40, with tray. 10 months old, in mint condition. I saw some selling for $30-35 without tray. I think with trays better, can put some toys on it for baby to occupy her attention. However if your baby has superpower thighs, may not be able to fit into the legroom of the bumbo seat. So the bumbo seat is good for babies with strong neck and can sit up to the period when she gets superpower thighs or when eager to crawl.