Almost all but the small netbooks come with a built in DVD/CD drive. Screen size -- this has to be balanced against the effect on portability. 15 inch seems to be a good compromise.
As well as reading reviews, I would spend some time at a showroom playing with a sample of models in your price range as things like styling and keyboard feel and screen quality are best judged hands on.
Don't be swayed by brand or price too much -- there are brands like Lenovo and Asus you may never have heard of but which are good in my opinion. Then some household brands which are not, though Samsung and Toshiba are usually safe choices.