I will try clear up some misconceptions for you.
Search engines do not care which platform you use to create your web pages. They look at the final HTML and judge that the same no matter which tool you used to create it.
There are factors that matter, like how you have structured your navigation, whether you have used keywords in your URL, page titles and anchor text. The nice thing about WordPress and other well designed CMS platforms is that they automatically handle much of the mechanics of those elements for you.
However, you still must alter the configuration and/or add plugins to fully optimize a WordPress blog for search engines. You could easily build a website by hand-coding that is far superior to the default WordPress configuration.
Another nice feature of WordPress is that it has to ping built-in. Pingo-matic, which is made by the same company that developed WordPress is installed by default and alerts search engines to your new posts so they are more likely to be promptly crawled by search engine spiders. However, pinging can be done by anyone, it is relatively easy to set up for any website and is certainly not anything exclusive to WordPress.
The bottom line is that WordPress sites are not treated differently. How you optimized and promote your website is what makes any difference that you see. You might find WordPress to be a tool that you prefer to make the work easier, but it has no significance to search engines.
As for your second question, search engines ignore dashes, so a domain with dashes is roughly the same as a domain without dashes.
There is one signal that makes a rather small difference that favors non-dashed names, but ever so slightly. Search engines, particularly Google use prominence as one of the 200+ signals that determine relevancy scores. Since the second and third words contained within a 3-word domain name would be 1 and 2 characters greater in prominence without dashes it might score slightly better. I don’t think that difference is enough to be concerned with.
Some folks prefer domains with dashes because they can make the multi-word phrase slightly more readable to humans. One of the best uses of dashes within domain names is to prevent the unintentional word combinations that could be awkward or embarrassing. For example, consider the following domain name for an online pen and pencil retailer without the dash. It could be a bit embarrassing if you didn’t separate the right words: