Yeps, Dual Format burners are the way to go these days. The price for one is almost the same as a single format burner. Basically getting the most bang for your buck kind of deal.
This also eliminates the problem of you having to worry about which format your home DVD player takes or whatnot. Nothing worst than having to have made a Movie but not able to play it because you do not have a compatible DVD player at home.
So yeah, you can burn both DVD-R, DVD-RW, DVD+R, DVD+RW, CD-R, CD-RW. The speed should be listed on the box of the burner. Usually it will be 4x for both DVD format, and I think 24x or 32x for the CD-R.