I'm not sure why you seem to hung up on only accessing WP from a nominated PC. Since WP is 100% web based, you can access/admin a site from any computer, tablet or mobile anywhere in the world. So maybe you're over-thinking this a little?
Yes - there are mobile version for tables and phones but they aren't mandatory. For example, I have the iOS app on my iPad but rarely use it as I can still do most things on the site using plain old Safari.