nah don't bother with Necronet Access, it is a pretty worthless skill. Lab Experience allows you to do revives so that's as far as you need to go up that skill tree.
Pretty much all survivor skills are useful in different ways, but the basically useless ones to get last after you already have all the other skills are Knife Combat, Radio Operation, and Necronet Access. Also, while Tagging is marginally more useful than those other skills I just listed (spraypainted messages are frequently used to mark entry points and revive points and such,) it's also one to get after everything else.