I know that, it's the reason why I only raise my skills to 80 and it's only when I get to a high enough level where all of my used skills are at 80 that I raise them higher. The only exceptions are Guns(or any of the other weapon skills), Lockpick and occasionally Repair which I raise to 100 through a combination of my base skill plus the bonuses I get off of clothing I wear a lot and my SPECIAL.
Comprehension is the most useful perk.
I personally disagree. I really prefer selling magazines to using them xP For perk-related reasons mostly, but also so that my character isn't crippled if she doesn't have a copy of Milsurp Review/Locksmith's Reader/what-have-you on her person at that moment. And also because it weakens my character for roleplay purposes.
That said, Comprehension is one of those perks that is really useful. It's up there with Toughness, Life Giver, Black Widow, Living Anatomy, & Strong Back.
OT: Depends on your build. For a Melee/Unarmed guy like me, the most important statistics are HP, DT, DR, Str, End, Survival, Sneak, and the appropriate weapon skills. With 7 points of Agl to get Slayer, of course. There is no "always most important" stat, but every character needs HP.
-Nukeknockout