The only mobs that could attack you are slimes, and they only attack if you do so first.
But only small ones and they are very rare, so conclusion: No mobs do not spawn, cattle on the other hand (like cows and pigs) does.

Hopes this helped you.

No hostile mobs dont but passive mobs do and wolfs plus all hostile mobs despawn

Only passive mobs such as farm animals, wild wolves, and ocalots (wild cats, unsure how to spell it) spawn in peaceful mode. Technically, all mobs spawn in peaceful, but they are removed before the entity and the mob model actually loads. In other words, all mobs spawn in all levels, including peaceful, but peaceful mode deletes hostile mob entities as well.