1) I beleive disk utility will format the CD-RW and DVD-RW disks, it will erase and format the discs too. Open disc utility and then go to the help menu. Search on CD-RW or DVD-RW and you will get the short explanation.
The finder, itunes, and disk utility can meet most basic disc handling needs, but w/ regard to Toast it used to be that it would enable use of third party drives and some features that should've been part of stock Mac OS.
2) Tosast Ti is good. It is ridiculously overpriced, but does go on sale. I would never have made the leap to buy it were it not for the sale. After buying it I found out that it is much more powerful for dealing with a multitude of video formats that iDVD won't handle. the downside is the interface, particularly for making DVD menus is horrible. The DVD creation is still in it's infancy for home user tools.