replacing drain pipe with RIDGID Model 246 Soil Pipe Cutter

Is replacing cast iron drain pipe something a diy can do I want to start
the job but i would like to know if it would be a good idea.also should I
replace it with cast or PVC Thank You

What size of pipe are we talking about, the bathroom sink and tub would normally be 1.5 inch galvanized. I guess to do it yourself, depend on your skill level and that is something we don't know. Regardless, if it is galvanized or cast, you should use PVC.

Removing cast iron is one thing. It can be difficult for a DIYer because you must cut it loose and then handle the weight. Others might describe drilling holes in the lead then prying the remaining lead out, but that is way more difficult to do than it is to writing how to do it. The best way to cut cast is with a snap cutter, but it can be done with a recip saw and special blade or with a grinder. The latter can be very dangerous and I would not advise it. The replacement pipes would normally be PVC which is connected to the remaining CI with a banded coupling also known as a no-hub. You must use extreme care if you are removing a vertical stack. It has to be clamped to joists and rafters or it will come down on top of you. Cast iron has one advantage to plastic. It is quite when water is running through it. PVC and ABS are noisy. Replacing with new cast iron is not a DIY job, and I would suggest having a plumber do the entire job for your safety.

pipes

That is like saying, "I want to work on my car. Is it something I can diy?" Without knowing what you want to do, and why, there is no way we can tell you. But with cast iron, unless you are just referring to the straight sections between floors, there is more to it than just "cut and replace".