If it were as easy as a one-word answer, yes. But to be truthful, not necessarily.
If your business sells only one or two kinds of an item, let's say it's one type of refrigerator with only three options, then you probably don't need a true "blog". However you should have an article base, explaining the options, why they're useful, what your manufacturing process is, and a gallery of photos of your refrigerators, so using standard "blog software" such as WordPress will make doing this quite easy, and will help your potential customers learn about your product.
However this scenario applies to less than probably 5% of businesses out there, so if you're doing anything remotely more involved than this, the answer is still most likely, yes.
A landing page is any page on your website or blog that you drive traffic to in order to produce a specific call to action or result of action.
Example: You have an ebook for sale that you want to promote to your newsletter. You create a landing page, describing the ebook and add the "call to action" which is the buy button. In your newsletter, you link to this landing page (as opposed to your main URL).
Example Two: You want to get more people to sign up for your newsletter. You create a page explaining why they should, what they'll get, and put the form in where they can sign up with their email address. That's a landing page. You then would link to it in your site's sidebar, or on your facebook page, or in your email signature, and that's how you direct the traffic to the landing page.
These days, it seems like people call themselves a "social media expert" because it's the hottest new career path. Reminds me of a time when anyone with Microsoft Front Page would call themselves a "web developer". Truth is, just knowing how facebook and twitter work on an operational level does not make one a social media expert any more than using a drag-and-drop WYSIWYG method of building a web site (full of extraneous code and bad color schemes, no less) makes one a web developer.
It's a broad classification at best, and unless you know what it is you're looking for (and let's face it, most businesses don't until their told), it's hard to generalize properly.
What it boils down to is knowing how to connect businesses to customers on a personal level. The days of showing an image of a blonde beauty, dripping with diamonds, and wearing a seductive, crimson pout in order to sell the latest lipstick are coming to an end, folks. Social media has made people want to be able to ask questions about a product, know more about how it's made, find out if it's the right product for them, and they want those answers from a human being - not a block of text your ad agency wrote up for your site.
A real social media expert excels in one or all of these things: Blogging strategy, content development and marketing, social networking presence and campaigns, customer service (with a gigantic, gleaming, virtual smile), storytelling, search engine optimization (to an extent, at least), knowing how to communicate with various target audiences (or even specializing in one type).
Finding the one that will work best with you and your business is the challenge, but make sure they can explain what it is they actually do and you're on the right path.