Good luck getting 2x devious.
For maximal survivability you want: acrobatics, shield block, doubleback, evasive edge, getaway edge, slippery escape edge.
Race: Arial for perma-fly and better dodge -OR- human for no vulns.
For spying and sneakiness you want improved hide and covert.
Then spend the rest on your traps.
Gentlewalk is super convenient for lots of things, but doesn't make you any more survivable. Helps you get certain scrolls. Makes flee/knife possible on mobs that see hidden, or are located in areas where you can't hide.
Scrolls only add to survivability in the sense that they give you extra options for stoneskin/aura/shield. They're also nerfed somewhat if you don't take arcane lore, which costs you more points.
Been a while since I had it, but if I remember how it works correctly then "thief waylay" would be nice on a pickpocket since they have nearly guaranteed steal on awake people. Waylay someone, rob them blind. Also good for setting up Empire ganks. Depends on how long the "freeze" effect lasts. If it's multiple ticks then it would work, otherwise not.