I mean seriously, when was the last time you saw a Japanese person carrying a semi-automatic in the back trunk of their automobile? Never, that's when.
Hahaha! True xD
Which God forsaken bit of gaikoku do you live? I don't think that's normal most places.
Kabukicho is not as bad a Roppongi, but yes, there are some rather dodgy places. If you're not looking for trouble then it won't be looking for you.
The Price Hotel is just above Seibu Shinjuku station, which is handy, but you'll probably never use that line (happens to be the line I live on!), only the JR station a few minutes walk away. which has far more connections. Tokyo has two pass card systems, PASMO and SUIKA. There is a difference, but they're interchangeable for most situations. As a visitor it won't matter which one you use. I think you can even use them in Osaka these days. You can only use these on the local trains. You have to buy another ticket for express trains. By the way, not all the Narita Express trains stop at Shinjuku, so watch out. It may be quicker to go to Tokyo and change to the Chuo line.