TDD or not TDD on a medium project with two guys, there you go...

TDD always
Or any kind of testing

Definitely TDD, proven to have less bugs later

TDD always

Ah yes "Todo Driven Development", my favourite type of development

TDD for life better BDD

TDD when appropriate. It can definitely slow you down especially when you're learning about the product as your building. TDD is good when you have an explicit spec of what done or right looks like and that's rarely the case.