If an effect says Foriysian Totem can't block, then it can't block any creatures.

The third ability normally lets Foriysian Totem block two creatures. If another effect also lets it block an additional creature, the effects are cumulative.

A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.