Which way can I setup how much text will be shown for posts on main page before 'read more' link (by default)? I would want some more amount of text shown than current one.
Thanks for help.

look at the virtual templates. Examine index.php and see what it points to and then examine that one.

OK, I found how it can be customized.
Montezuma Options -> Sub-templates -> postformat.php
change here 55 (number of words) to your value
Thanks for tip, I am meeting with wordpress only.