1) Yes. You can start off doing only logo's. Better to have more versatility, but we all have to start somewhere.
2) Portfolio - If you already have commissions, put them in there. Between 7 and 10 is a nice amount. Print on good quality paper. If it's stuff you haven't been hired to do, make sure its clean stuff; good, high resolution images; If it's a digital portfolio, I'd add a watermark for extra security. This also tells people "this image belongs to someone, no use w/o permission". The "good clean, high rez" stuff obviously applies to anything you're hired to do as well.
Doctors heal you, Artists immortalize you.
"Those who can, do. Those who can't, teach" - bullshit.
The usual staples for anatomy: