1.There is a risk that your renewal application of your
TN, with an approved I-140, will be refused though most border officers will renew it for you;
2. One walkaround is to get a H1-b, if there is no quota issue for you. It takes only 15 calendar days with a premium process (of course, $1000.oo);
3. There is no problem for your I-485 to be processed while you are holding a TN