Well for your first question...
1. No the stock fpr will handle everything. You can switch later if you decide to go more boost/fuel. MPG will not change like I said before
2. The only other thing you could do is test the fpr, check how much fuel your getting at the rail, if any. Check your efi/fuel pump fuse and relay. Other than that man, its not bad to just change it. 100-150$ isn't a bad investment.
And as far as dropping the tank. Jack up car(high as your jack will go imo) put on jack stands. Then use the jack to lower the tank once you removed the straps. Reverse installation. Pretty simple man.
