Lexus Es 300 2002 Tires/Struts

Hello, I have a Lexus ES 300 2002. Few months ago, I started hearing loud road noise coming from front tires that would increase with the speed, I was told that tires had feathered due to bent front shocks and I would need new shocks for front, I had replaced these same shocks in 2007 and put on 40,000 miles since. I had also bought 4 new Michelin Weatherwise from Costco in 2008 and put on 30,000 miles since. Also, my car is suddenly giving me from 25 miles/gallon to 13 miles/gallon. Here are my questions.

1. Is the life of these struts only 3 years or 40,000 miles? Is there generally a warranty on struts?

2. Can bent struts cause tires to feather/warp so bad that they will cause extreme road noise especially for Lexus?

3. Can bad tires cause the mileage to drop from 25 miles/gallon to almost 13 miles/gallon?

4. If I were to change the struts, get the alignment done and buy new tires, would it fix my issue of road noise and mileage?