I Have a lot of questions of a pet rat. Can someone help me for 10pts?

listen..I had 2 pet rats.."Oreo" and "Nilla" they both died of tumors...VERY common in rats almost 90 percent one doctor told us!!! but they are great if you hold them more...;P rats that are not held do bite...both my rats nipped, but it never hurt us...they were scared about somethin...good luck ;P