What you need to start?

You _can_ but they're not the best choice for hogging the interior of a bowl. Often you have to reach farther than they can without chatter, so you need a longer gouge with sturdy section. Long and strong or the cylindrical gouges will do better. Nice 3/8 U-shaped flute "bowl" gouge will reach. Recommend a chuck for ease of operation and best enjoyment, but a faceplate will do.

Yes. Keep the tool rest as close in as you can - a lot of what bowl tools buy you is extra overhang ability form stiffer, stronger tools. Then spend $15 or so making an Oland-type tool.

As few as none, if cost is an issue - faceplates are much cheaper, and you probably even own one or more already.

Take a look at my web site under bowl turning for information on making and using Oland tools for bowls and turning them without a chuck. I have a chuck and various bowl gouges and still prefer to use faceplates, glue blocks and Oland tools.