The only one that is necessary is the second one--
if the attacker doesn't know anything about the key.
A one-time pad is a perfect cipher, and as a perfect cipher,
the computation power of the adversary is irrelevant.
The first one is not true.
The second statement is true, because if an attacker knows something about the key,
she or he will know something about the message,
which would compromise the confidentiality.
It is not necessary to assume that the attacker cannot modify the message.
Modifying the message only effects the integrity of the message,
but that does not effect the confidentiality.