When in the matrix, a program (including an avatar) has an effective Athletics skill equal to the rating of the deck running it. A rating N deck is probably a resources N extenditure, so expect inner sactums to be guarded by programs with an Athletics of 5 and possibly 6.
The "essence" of a deck is equal to the essence of the person who maintains the system. I'd make it two purchases: the hardware has an Essence proportional to its resource expenditure (say, N-3, decks are expensive); the software has an Athletics (or Martial Arts? maybe other than that, too) skill proprotional to its resource expendiutre (say, N-1, software can be pretty cheap).
Athletics charms are available as Deck Charms, off of the Crafts skill. A character must both know the charm (having spent experience to learn it) and have it installed in his deck (requiring Crafts (Electronics) rolls) in order to use it.
That's slightly problematic: there are absolutely zero adepts born in the 2060 setting in universe before the party; basing "cool decker schtick" on adeptly tricks breaks the setting pretty badly. I'd just have the monetary expenditure.
A program that is not acting as an avatar has an essence of 0, and so have spare essence motes equal to its willpower, which is usually low, but may be raised as high as the willpower of the programmer (programmers are notoriously willful, "herding cats" and all that). There may be charms that allow a programmer to give his programs more "juice." Programs may be taught Deck Chams using the essence of the deck they're on, meaning that if on a deck build to give those capabilities, they can exploit them to use Deck Charms.
Other charms may also be adaptable into deck charms. The process for use is the same: the programmer must learn the charm, the deck must have a high enough rating to support the charm, and the charm must be installed in the deck before it can be used.
This means that yes, buying a better deck and good chips is helpful, but not as overwhelming as in Shadowrun.
(Otaku, who deck using a "virtual deck" in their brains, automatically have all deck charms they know and qualify for "installed" in their "deck." Adept deckers probably have a scene length Lore charm that allows them to use their other charms in the matrix, but may need to design and install their own charm chips to use it effectively--which is why truely leet deckers have custom-modified decks.) As above, the decision that existing truely leet deckers have custom-modified decks because they're actually adept deckerss horribly breaks the setting: that's really not the game I want to run right now, though it could make a kick-ass different game.
--jesse
--bts