Hi there,

You can use css to hide the readmore and the titles.

.gal_item .post-title { display:none;}
.gal_item .readmore { display:none;}

I would say the easiest way would be to use the WordPress gallery, on the page you’ve made for the sub gallery, click add media, then create gallery and select the images you want to use. http://screencast.com/t/jZuqsZ7Ef4

You can then choose what the images link to (attachment page or media file) on the options which appear for the gallery. This way you won’t have to create posts for each image.