The two and three column templates are great for displaying lots of posts that all have similar content. When using these templates, make sure that the titles, subtitles, and teasers of each post are similar lengths. Consistent use of images or videos is also important for these templates.
The “Post” post type is the default post type on your site. The majority of your content will most likely use the “Post” post type. Use this post type unless your content fits into a more specific category that fits in with another type.