Just too chime in, I get an email from these guys once a week (I’m a domain name junkie and think someone should start domianers anonymous) and its a pure scam.
Anyway, your second question states, “Can an international company or anyone buy a domain with the brand name that is my company business name?”
From what I understand this will depend on the rules operated by the registry for the tld, but in general yes they can.
To defend your trademark across all tlds you would first have to have been granted the trademark protection for every country for the tld eg if your disputing a .co.uk, you would need a UK trademark etc
This becomes very very expensive very quickly and is really only viable for big corporations with very deep pockets such as Microsoft, Coca-Cola, McDonalds etc
So the moral of the story is be pre-emptive and try and register domain names for the TLDs you think you could possibly need for the next 10 years.
Also just to throw in a link, CasinoMesiter linked to USPTO which looks after trademarks in the US, here is the website for the European Trademark website http://oami.europa.eu/en/default.htm using one application form you can apply for a trademark in every EU country (rather than apply in each country seperatly).