I’m no expert, but I can answer some of your questions:
1: Zombie children, being small, are pretty agile (for a zombie). Your encumberance is high enough that it will give you a fairly hefty penalty to your to-hit rolls, yes. Together, you will have a moderately tricky time hitting zombie children. To fix this, you should level your melee skill, and try using a more accurate weapon (one with a bigger bonus to hit). EDIT: Also, try lowering your torso encumberance. 68 is really, really high - I rarely go above mid 20s until I have endgame level armour, that is WORTH the encumberance costs.
2: The main use I can think off is making molotovs. I don’t use many myself, but some people swear by them. And if you are taking on a horde, they can certainly up your chances greatly. If you have the Ethanol Burner CMB, you can also use them to power Bionics.
3: No clue, I don’t do vehicles. Sorry.
4: Stimulants (like meth) are GREAT - they give short boosts to your combat stats. If you find yourself backed into a corner, taking a hit of meth can save your life by greatly increasing your combat ability. Stuff like weed is much less useful - its really only good for morale. Morale’s main use is generating Focus, which is needed to gain Exp. Basically, being in a good mood makes you level faster, drugs can put you in a good mood. Risky though.
5: I think you can get some mech skill by doing stuff like repairing metal items with a soldering iron… but by far the most common way is to find the book “Under the Hood”. Its pretty common, and can raise your mechanics skill to 3. You only need mechanics 1 to install/remove from cars.
Hope this helps!
