My sites get plenty of spam comments. How can I control them??

Everyone says that to look onto social media networks to find out which is trending in industry right now. I would like to know that what are the methods you use to find out what's trending.

In the skyscraper technique, when it comes to outreach I see that many marketers says to mail other blogger offering them some good content which they had already shared. Is this a really effective method? I mean i had tried it but the success rate to me is less than 1%.

If any body will provide me some tips about how to optimize my emails for mobile devices. Then it will be really helpful.

I had tried to use Google Keyword Planner to find Long Tail Keywords. But to my surprise I haven't found much. What are the alternatives of Google Keyword Planner to find Long Tail Keywords?

What is the post frequency you like to maintain in your newly started forum? I mean a new forum needs many types of posts such as how tos, tutorials, discussions etc, which one you publish at what time gap.

Some of the SEO bloggers suggest me that the length of blog post effects the rankings. As the longer the posts the more they will be considered as insightful by google. Is it true??

I have been trying to test my landing pages by showing them to complete strangers. This testing method is great but i had got some reviews that tells me they haven't understand a bit & some others said it was a good experience. How could you guys justify this??

Does the social signals can effect the Bing SERP?

In the Google webmasters tool of mine, I found some of my keywords avg position ranking 15-20. But when i search for those keywords in the google search i could not find them in the first 10 pages. Why is it so??