Facebook's lead generation works fine for me. I have generated around 1000 leads from the potential audience who are looking for Home Energy switching however my campaign for car insurance partially failed to generate sufficient leads.
There is no specific rules but avoid duplicate content as much possible.
Normally, It is not bad if you use an article in 5 to 6 websites. Make sure that articles published in your website should not be published elsewhere. You can promote the link of your website's article but not the entire article with content.
your robots.txt file is perfect.
If you have any demo site or duplicate pages of those pages which are likely to rank then pls mention the directory path in robot.txt and say Google not to index them. This way you can prevent your site from duplicate content penalty from google.
i.e. I have a demo site that I would like to prevent from indexing so I put the robot.txt as below.
There are two ways to make money through blog.
1: Set up google adsense in your blog
2: Approach business owners to publish guest post on your blog. You should first identify your visitors and also you should categorize your blog like travel blog, health or fitness blog, fashion blog etc. To earn money through guest posts, rather than making your blog general, you should go with a specific niche.