your friend is right about jacking off beforehand to make you last longer. jacking off 5 times a day will probably make you last longer too (even if it's not 2 hours prior to having sex) because your sex drive is a lot lower.

and all alcohol is gonna do is make it harder to get up, or not as hard when you do get it up. yeah, it'll make you last longer, but it won't be better for your partner (i say this based on my own experiences with drunken sex)