To answer your final question, yes but not really. You can definitely use AdWord keyword planner tool to get solid organic search volume estimates. However, don’t just stop there. Leverage other tools to find longer tail variations you can map against various stages of the buyer journey. I like to use SEMrush, Keyword and Google autosuggest.

Because great content requires a deep understanding of the main idea (e.g., “ac repair houston”) and the supporting subtopics that require coverage (e.g., “central ac vs portable ac systems”) and the common issues that users seek answers for (e.g., “freon,” “refrigeration loops,” “coolant refills,” “troubleshooting”), the effectiveness of a keyword reporting tool is only as strong as the SEO pro using it.
If you’re serious about making a success of blogging, you need a keyword research tool like this. Such tools can also prove useful before you even begin. If you have several ideas, you can do your research up-front, and see which niche gives you the most chance of success, and which is already highly competitive. Working this out can save you an awful lot of time and money in the long run.
In order to know which keywords to target, it's essential to not only understand the demand for a given term or phrase, but also the work required to achieve high rankings. If big brands take the top 10 results and you're just starting out on the web, the uphill battle for rankings can take years of effort. This is why it's essential to understand keyword difficulty.
Long Tail Pro is a keyword research tool. Keyword research helps you find exact keywords that people are actually searching for. Some keywords are high competition (meaning it is harder to rank for on your site) and some have lower competition (easier for you to rank). How does Long Tail Pro work? First it finds the actual keywords for you based on the ‘seed keywords’ that you input. Then it helps you analyze the competition to see which keywords will be harder or easier for you to rank. How does this benefit you? You can take those ‘easier to rank’ keywords and use them in your content to increase search engine traffic to your site.
The relevant keywords that you target with your ads will bring the right audience to your website. Showing your ads to people that type relevant keywords will result in higher click-through rate (CTR), lower cost-per-click (CPC) and higher conversion rates for your business. As a result, you will spend less money on advertising and generate a better return on investment.
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).