If another effect causes one of the returned permanents to become a creature and sets its power and toughness as it does so, that creature will have that power and toughness; it won't be 5/5. Notably, crewing a Vehicle does not set its power and toughness, so a Vehicle will remain a 5/5 creature if you crew it.

An Equipment without reconfigure that's also a creature can't be attached to anything. You can activate its equip ability, but it won't become attached.

An artifact creature, land creature, or enchantment creature returned this way will be a 5/5 creature and will be an Elemental in addition to its other creature types.