Resizing Thumbnails Pics in Gallery photos and Slideshow Layouts

1.
I’ve tried to resize the the thumbnail pictures in the gallery photos layout and in the Slideshow layout by adjusting the css. I added widths and heights to the following:

.ims-gallery .ims-img img
and
#ims-thumbs .thumbs li img

I am trying to enlarge the thumbnails a bit also keeping the images square in proportion.

I get the desired size but the images are very pixelated. I need help figuring out how to adjust theses sizes properly.

2.
I also need to have the images cropped at top center as opposed to just center. I realize you can adjust this in the admin area or each gallery and re-crop each image individualy. But I would like the default to be set to top center.

Thanks in Advance for the Help!

http://wordpress.org/extend/plugins/image-store/