1) Enhance Ability, which only works on yourself, combined with the Imbue Item feat. Pay special attention to the Charm rules on page 88.
2) It's too campaign dependent for a single generic solution. There are numerous solutions proposed and generated, from Blood Throne's Ascendant Technology to the Tech Adept, but all were designed with specific campaigns and genres in mind.
3) A 'masterwork medical kit' would have good drugs, lots of bandages, minor surgical tools, possibly even a portable defibrillator. Like all masterwork tools, it would grant a bonus on Medicine checks (or enhance an existing bonus).
4) Shrugging off damage depends upon several things; the amount of damage commonly dealt, the availability of armor, the level of the campaign, the generosity of conviction regain, and the individual character builds all affect the danger level of the campaign. Smart tactics, such as Combined Attack, will challenge even the toughest characters.
If an individual Narrator or group decides that it's just too easy then increasing the base difficulty of Toughness saves is really all that's required. Increasing it to 20 + Damage quickly results in a game where anyone (including small children) can deliver a one punch knockout to almost anyone else; increasing the base to 25 + Damage makes combat all but suicidal. Alternatively, you can lower the base save to make the game even more survivable ( 12 + or 10 + means that Conviction will usually allow the character to succeed ).
If you've got any other questions or concerns, please feel free to ask here or on the True20 forums.
