Can I take 1 Advil (ibuprofen 200mg) and 2 alka seltzer plus (acetaminophen 325mg each) together?

Not recommended. Because Ibuprofen decreases effects of alka-seltzer, increase potassium levels in the blood and alka-seltzer will increase the level or effect of ibuprofen. Not recommended! see a pcp for more information.
Yes. You can safely take ibuprophen and Acetaminophen together in the amounts that you are taking. You can increase the ibuprophen to 600 mg if you need additional pain relief.