First Aid VS Doctor

[Dr.Joto]

Advantages and event specific checks, because doctor seems like a straight upgrade from where I see it. Also, how good is science?

[Gorgeous Freeman]

I usually choose doctor over first aid. Doctor heals more and you can fix crippled limbs, first aid is more useful for healing a smaller amount of hit points.

[AdrianCypher]

Science is very useful for a few side quests (e.g. Skynet), but not essential to finishe the game. You should boost it up to the max with books (plenty to be found in VC) and only then use your Skill Points.

[stcaFylnO]

First Aid: Only heals a few HP a few times, then messages appear that character is too tired to use it and they have to wait. Also, 1st Aid kits are in short supply and finite use. So, open inventory and guzzle Stims instead; Quick Pockets only requires two AP to enter inventory, so guzzle tons of them, reload both weapons, then exit. The two kits provide 20% and 40% bonuses.

Doctor: Rarely needed, incase a character needs to have a critical debuff cured. Save the Doctor Bags for real emergencies. My memory is fuzzy, but I think it is a 75% skill check for dialogue in Vault 8 (Vault City) with Dr. Troy and maybe the nearby medical computer (for Jet cure and Strength mod chip info?). It is also possible to visit an NPC doctors to remove debuffs. The bags provide 40% bonus, but won't help with skill checks. I bet the character can only use it a few times at once, but I've only needed it a few times ever.

Science: Skynet version of robotic companion is very high... don't remember, like >120? So, if playing on Normal difficulty, change to Easy for a 20% boost, or if Hard, then go to Easy for 30% boost. There are no items to boost skill checks. Science does help hack learning stations for some XP and computers for events, but I've mostly gotten by with 70-90%. If fail, reload.

Note: Hoard Skill Points (up to 99). If having trouble passing a check, increase skill between save/load cycles and test for threshold. Use consumables to lower stats, change to a higher difficulty setting, spend points, pass time to reset stats, change to lower difficulty, then test threshold. Just watch out for addiction issues. This also works for skill books and there are so many in game, you can probably boost First Aid, Doctor, Science, Repair, and Outdoorsman without using any level points.

Refs:
http://fallout.wikia.com/wiki/Fallout_2_skill_books (partial volume, I have dozens unused).
http://user.tninet.se/~jyg699a/fallout2.html (exhaustive resource).
http://www.gamefaqs.com/pc/63576-fallout-2/faqs
http://fallout.gamepedia.com/Portal:Fallout_2
http://fallout.wikia.com/wiki/Fallout_2
http://strategywiki.org/wiki/Fallout_2