Lockpicks offer a one time bonus to your Open Lock skill, useful for the most difficult locks. However, you need at least one skill point in Open Lock to even use it.
Healing Kits allow you to make a "healing check" of 1d20 + your heal kill + the bonus on the kit. If you have a poison and/or disease it will remove the affliction if the healing check > difficulty of poison/disease. It will also heal the amount OF the healing check. It will also ALWAYS roll 20 out of combat.
So let's say you're at 20 out of 50 HP with a 23 DC poison and a 26 DC disease. You have 1 Heal skill and a +3 Healing Kit. You use the kit out of combat. Thus your roll is 20 + 1 + 3 = 24. So you remove the poison (but not the EFFECTS of the poison, just the poison itself) and heal yourself for 24 HP. You do NOT remove the disease since the difficulty is 26 -- for that you need more healing skill or a better healing kit.
Healing kits are what keeps characters with no healing skill going in long combats or when sleeping is not an option.
This is false -- during combat you'll mainly want to use potions UNLESS you're investing massive points into the Heal skill. Even then most modules/campaigns wind up offering healing potions far stronger and more efficient than healing kits -- but healing kits are amazing at low levels out of combat. Not so much an issue in the original campaign since you can rest just about everywhere, though.
thanks for the quick replies! i'm glad i saved the healkits then. i took one critcal potion so far and it healed for a LOT less than i thought it was going to ha ha.
A Cure Critical Wounds potion (on hardcore rules, meaning the rules apply equally to you and enemies) will deal 4d8 + 7 HP which is 18 + 7 which is 25 HP on average both in and out of combat. With 0 Heal skill and a +1 Healing Kit you'll only heal for 11.5 average per kit in combat (but 21 per kit out of combat).
Eventually (chapter 3 and beyond, possibly chapter 2) you'll find "Potions of Heal" which heal you back to full health, period -- whether that be 20 HP or 200 HP. Those rather outclass Healing Kits once you find them.