OK Kawaiineko , don't burst your bubble here. The people answering your question are anything but rude, it may sound rude to you but that's the reality of it so try to deal with it.
Anyways, back to your question. Western foods. YES they are widely available. Do you know "CosCo" ? you can shop at your hearts contents for all the western food and product there. McDonalds, Starbucks, Krispy Cream, Shakeys, Pizza Hut, Bagel Store, HardRock are everywhere, even Windys.
If money is not a problem and you want more expensive item, look for a store like Daimaru or head to Midtown in Roppongi Hills.
You want more exotic product? Thai, Vietnam, Indian restuarant are also widely available.
So hopefully no violent reaction to this post of mine
About visa, Japan is one of the countries with the strictiest policy concerning visa application. So it is not easy. It never was, are and will be