"-" Are better for SEO than "_" keep that in mind. And yes having a keyword rich domain is an advantage to rank your site well.
Domain name affects the SERPs of a website mainly in two ways. 1. The Keywords in the name of domain are considered to be of high relevance and given high priority if the same keywords are searched. 2. The extention of the domain directly affects its SEO. Google gives low priority to Free Domains like .co.cc and .co.nr and .tk Google gives low priority to cheaper domain names like .info and .name High priority is given to trusted domain name extentions like .mil .edu .gov etc A little much local priority is given to local (country specific) domain name in geo targeting.
Do you have a source to back up this claim? I seem to remember reading somewhere (possibly on Matt Cutts' blog) that this was not the case.
To answer your question, there is no difference between: domain_name.com/wedding-hotel domain_name.com/wedding-hotel or even domain_name.com/weddinghotel They will all carry the same weight.
In a way it would affect SEO but not as much as one way quality links do. If your domain name is your main keyword then it would help but most of the time the domain name is not available.
Yes Domain name affect seo. Search engines tends to know that what is the subject or topic of content on any particular website. so if you use your main keyword in domain it must be good for your website.
It's always a good idea to have one of your main keywords in your domain. Also, it's good practice to keep your domain short and easy for visitors to remember. If the .com version is available, choose that over the others.
The domain extension weighting is bullshit. I have some kickass .infos ranking, and I buy more all the time. Your link quality and volume determines your rankings, not your TLD.
I'll say that my best advice is to focus on building the best possible content for your site, update it with some frequency, generously link to other relevant sites, and use some basic search engine SEO tactics without crossing the line into "black hat" or other dangerous and unethical tricks, and you'll do well in the search results. Focus on findability.
There's some weightage but I wouldn't worry too much about it. Your URL also has weightage and you have more control over it. The rest of it is, like the others said, quality and quantity of links and keywords, the usual stuff.
I have a competitor who registered a keyword rich domain, threw up an almost blank Wordpress blog using the thesis theme, probably did external SEO such as listing with technorati, feedburner, google analytics etc ... and the sonfoabitch is right below my site's listing and I worked my ass off to rank. so... it does help, more than you might think. I wish your reply was accurate, I really do but it doesn't look that way from where I sit.
I'd have to add this to what's been said already: If who ever you're competing with has done their homework, you're going to have to do more. What I mean is... if a site is crap, has crappy backlinks or no backlinks, or committed one or more SEO sins, if there are not better contenders then it will rank. From what I can see of Google's observable behavior, the algorithm considers one set of considerations to determine rank, there's no reason for the algo to use a second tier of considerations if there are no other contenders. You can have a crappy site, and if there are no other contenders, you win by default. It's the challenger who then forces the algo to use a second tier of considerations to determine ranking. I'm of the opinion that's why some crappy sites rank, and every one falls all over themselves to explain why X did well and Y did not.