@Bishop
Yes and no.
Yes, keywords are always going to help. Natural language is going to help the most. If you're making up a sentence/title for the sole purpose of having the keyword in there, then it doesn't make sense to do it.
Google does get that words and concepts are related - ie synonyms.
Number of words - whatever it takes to get your point across. Short ones, if done well can be just a powerful as a novel.
Think first about your reader.
Write about plumbing, cleaning hair out of drains, feature a device that traps hair before it gets into the drain (and a link to the device on amazon so they can buy it and you can make 3 cents commission), discuss different types of DIY drain and pipe cleaners - which ones hurt your pipes, which ones work. Discuss tree roots in drains. Another post on what the environmental impact on the chemicals that kill the tree roots. Discuss septic systems. Write about which trees cause the most trouble with drains in the Las Vegas area. Write what special types of pipes are best for homes in Las Vegas. Write what might be unique about the plumbing industry in the Las Vegas area. Mix it all up, be consistent.
All of the posts are designed to be useful someone looking for an expert.
All these together will give search engines (esp the big G) the clear picture what your business is about, where you are.
And remember, quality beats quantity. Write for your readers.
Then tweet/FB/promote your blog posts.
And most importantly, don't put all your marketing efforts into one basket. A blog, Adwords, G+, the web it's all only one channel - albeit an important one.
Here endeth the sermon... (whew!)