re: I need to change to about 155*124px landscape- how do I tweak the template so those images fit?
Here’s the doc that explains how to change the image size. Make sure to read the exception notes about Tile Plus. If you change the image size, then you’ll need to adjust the tile size which leads me to the answer to your next question…
re: Also, this would require a two column layout – what is the shortcode for that?
Here’s the doc for how to change the tile size. There is no specific short code to enforce a specific number of columns. The number of columns is directly related to the content width of the theme. So if the content width of the theme will allow 4 wide, then you’ll get 4 columns. NOw, if you have a responsive theme, the number of columns will depend on the content width of the theme based on the screen size of the visiting user. So, you will not have any real control in a responsive theme. My suggestion is to pick a tile size that fit the content within the tile nicely and let the number of columns be what they are on whatever screen size and content width of the theme be as they are.
Hope that helps.