You did a great thing as Drill Buckets as well as the Electric Rake (leaf rake + car battery, rakes are in hardware store, battery is on a dumpster in an alley across from the hardware store) are probably the two best ways to boost your PP. I got Chuck to level 5 in just under 2 hours doing that.

I've been wondering why they let you buy Zombrex in the pawn shop, for a couple reasons:

1. The game is timed and after 8:00-9:00 PM it ends automatically depending on what you're doing; in other words it's not like you can give her more than one shot of Zombrex anyway; when you do it forces you through to the next part of the game, where you fight the boss, and depending on how THAT goes you get an ending.

2. *slight spoiler* you can get it from the ambulance for free before the bike mission, in fact the game FORCES you to get it before you can progress the story

Maybe it's just there for the money achievement. I never got the chance to find out if it carried over, but for the reasons above it doesn't really matter anyways. Could be there for the full game too.