Things like page width etc should never be set in template code. This is the realm of CSS.
1. The shortcode does have a post_formats parameter which when set to true should work. But it doesn’t right now for some reason, so have logged as bug for now. Should be fixed in next release.
2. To create a template with a column layout, you really need some kind of fusion of the gallery template and blog template. The gallery template includes code for creating the css selectors to produce the column layout, but the blog template brings in the post formats and post content.
There is no problem with creating extra templates – that is what they are there for.