what other attribute is available on <hr /> tag apart from width and color

Answer 1

http://www.w3schools.com/tags/tag_hr.asp

<hr> supports size, width, align, noshade (all 4 obsolete, using css instead is recommended), color (non-standardized), plus the global attributes and the event attributes.

http://www.w3schools.com/tags/ref_standardattributes.asp
http://www.w3schools.com/tags/ref_eventattributes.asp

Answer 2

height