Actually, Adobe is not fully to blame here. The IDPF specifications of the the ePUB format are sometimes vague or open to interpretation. According to those specifications, not the whole CSS2 and XHTML format should be supported.
However, small-caps should be according to the specifications.
For smaller <hr /> you can always use something like:
Code:
hr.small {
margin-left: 30%;
margin-right: 30%;
}
If you use this class, you would get a centered line 40% of the screen width.