While sharing photos is a great way to engage users, the Live Feed is limited to four photos per post. If you have a gallery to share, upload it to Facebook first (or any other media hosting site) and link to the Live Feed.
Notice the character counter in the bottom right corner? It won't stop you from posting long messages, but keep your posts under 200 characters to grab and maintain the attention of your readers.
Keep the push notifications to less than four per week. Your app users are more likely to keep them turned on that way!