Can I use my mtgox BTC balance on the mtgox checkout button/payment platform while my account is pending verification ? Like purchase goods and services from people who use the mtgox merchant tools to accept BTC on their sites.
Yes, verification is only for increasing the amount of BTC and other currency you can move
"up to 10x your current daily limit, and up to 5x your current monthly limit"
through their service. It also enables you to use other services with mtgox such as dwolla.