nops for pages within the domain you should use '-' to separate it instead of '_'.

The reason why you should not do this in the main domain is because it looks spammy to many people as this is the format that most spammers use when buying keyword rich domain names...

Let’s talk completely about branding, I would never recommend you to go for .co domain when .com and co.uk is already taken by other companies...

It’s always an advantage to me to add keyword in the domain name but don’t push it too much if you are not getting it focus more on branding and choose a domain name that is easy to remember.

For separating keywords in the domain i would say do not use it and if it is necessary then use ‘-’ instead of ‘_’.

Hope this help!

To be honest, I f i would be at your place I wouldn’t have used that and if it was available I would have delete it till now for few specific reasons...

1. This has no impact from the SEO point of view and search engine is not getting or collecting any information from this...so why write more?
2. If the Meta Keyword tag is smartly inserted then it can be dangerous and this is because you are seriously helping your competitors to see what keywords are you targeting on the page and then he can alter his strategies accordingly to outrank you in search engine from the desired key phrases.

Hope this helps!