In your hypothetical, party one is the guilty one. By lying, they've altered the situation and therefore doesn't actually have party two's consent (in the same way "stealthing" changes the equation).

Sure a state of intoxication can remove the ability to consent and that is something the two need to discuss beforehand too, but if here both are equally drunk or they agreed to it at any level of drunkenness, nobody can read minds so going by the information available to any person we can say there was consent because they agreed beforehand. If any part specifies "it's ok unless we get too drunk" then it's a different case of course.

I don't fully understand what you mean in the second question, is part one agreeing to pretend to be blacked out but then blacks themselves out without part two knowing? Or is part one not knowing they are getting knocked out drunk? Because in the first case, where Person 1 agrees to have sex when pretending to be blacked out but then secretly blacks themselves out then person 2 is innocent and if anything the victim since they consented to having sex with the other person pretending to be in an intoxicated state and not necessarily actually being in that state. If it's the second scenario then person 2 is completely guilty because person 1 did not agree to having sex while being blacked out