Is there a preferable method for the average worker in these modern times to fulfill the obligation of zakaat on wealth? Also is there any concern regarding food products ( flour, grains etc) in the west on which nonMuslims may not have paid zakaat on? Or is it assumed halal without proof of being haraam?

Zakat is wajib if you have any of the nine things which are related to zakat, or if you have merchandises.
If not, you do not need to pay zakat, but you need to pay khoms (20% of what remains from your earnings during the year).