FontSquirrel is your best resource. Their "@font-face generator" creates code that will work with all the modern browsers.
What they do is well-explained but behind the scenes it's pretty complicated. You can read up on the CSS aspects on Paul Irish's blog.
Edit
I just realized that nobody has answered your real question...
1.) Myriad Pro
is a family of fonts, implemented as a collection of files, with names like Myriad Pro.otf
, Myriad Pro Bold.otf
, and so forth. (The actual names are OS-specific.) Myriad Pro Bold Condensed
is one of those files. I don't know if it comes with the standard package or whether it costs extra.
2.) You cannot "emulate" this. You can either use the actual font on your webpage (via the @font-face embedding method described above), or create a graphic. The designers probably expect you to create graphics, because designers [tirade deleted] when it comes to implementation.
3.) As has been pointed out, embedding supposedly requires an appropriate license, and I don't know you can get such a license for this particular face. ("Supposedly", because [tirade deleted], but I'm not a lawyer.)