Software applications which do not support OpenType layout features (check which software does support OTF features) can only display the default forms of letters and numbers. Typotheque fonts designed for small sizes usually use Old Style figures, while fonts designed for headlines use Lining figures.
Yes you can. Our CSS is designed to recognise local fonts, and if the given font is installed locally it is used first. In that case the webfonts are not used, so no bandwidth is consumed.
Regular Typotheque fonts support over 100 languages and advanced typographic features such as small caps, different numeral styles, alternative characters and special symbols. Web browsers, however, can access only a small fraction of those characters. Removing these inaccessible features makes the files much smaller, so they download much quicker.