Meta.Domains is a professional hobby. You may be offered some domains which could become a good alternative (replacement or supporting domain) to your current site address.
You can trust Meta.Business 100 percent, but this is not even neceessary, because actual transactions will take place between buyers and marketplaces. All the seller does is negotiating on price and terms, and giving information, answering questions.
Money and domains change hands directly via marketplaces, which can be global ones like Godaddy/Dan/Afternic network, Sedo; OR preferably registrar marketplaces. Registrar marketplaces are internal marketplaces of some registrars such as DYNADOT, Epik, Namesilo. Registrar marketplaces save time. They are perfect for buyers. For sellers, they are less perfect because buyer info is anonymous.
.COM is the king, because it is the default. Currently there are over 4000 extensions. In this crowd of new extensions, .com shines brighter. You may not like .com, but if you have a long or 2+ word domain, try to make sure you also have the .com version of your keyword.
If you used a domain for a long time, and decided to make an upgrade, cool, it may help, but keep your old domain for a while to catch incoming traffic and emails.
New tlds may do well, and can sell for up to 6 figures.
.com, net, . org, .biz, .info are established global extensions.
So are .mobi, .tel, .asia, but they are less popular.
Country codes are great in their respective countries. Sometimes they are number 1 choice at their homeland. But outside their place of operation, they may look awkward if used as the main domain.