Glad you like the theme and thanks for your purchase! For portfolio items, pls have a look at the file style.css in the theme directory.
The hover styles are located starting from line number 150 of this file.
The image styling is around line number 499. Also, to speed up your customization efforts, I would recommend that you have a look at Chrome developer tools or Firebug as explained here –
https://www.livemeshthemes.com/support/forums/topic/how-to-fix-a-few-styling-issues-instantly/