I am trying to replace some old (perhaps 60 or more years) cast iron sewer line that rns into my basement with plastic. I went to Lowes and they have like 3 different brand and colors of pipes that says "sewer" on them .. they were white, green, and gray in color .. i ended up buying the white one because it was the cheapest ($8 / 10 feet pipe).. here are my questions:

1- Do the colors mean anything? What type do u recommend?

2- I have 2 use those black flex rubber coupling that have those screw rings (sorry don't know proper name) in a couple of places .. how tight can i make them? i am afraid that i should have bought the more rigid pipes since i have to use these type of coupling

3- what is the best way to cut the old cast iron pipe .. i am afraid that it would crack .. specially at the end where it eventually goes under the ground ..

Thanks for your help and suggestions.