Alcohol can't completely wipe off memory, if you had an intercourse, you will remember it in flashes, no matter what.
As CurfewX correctly mentioned your questions are not in alignment to our forum, we can't offer you any further assistance until you are not relevant to HIV prevention.
This will be my final comment, since this is an HIV prevention forum, not a "what happened when I blacked out?" forum.
You would have noticeable pain.
Having anal sex without realizing it is a completely unrealistic scenario.