The default entries, if you don't put anything into gamusersettings.ini is as follows.

[Oz-Ark Structures]
IndustrialForgeSlotCount=150
IndustrialForgeCraftingSpeed=1.0
ReplicatorSlotCount=600
ReplicatorCraftingSpeed=12.0
FabricatorSlotCount=150
FabricatorCraftingSpeed=1.0
ChemBenchSlotCount=150
ChemBenchCraftingSpeed=4.0
IndustrialGrillSlotCount=150
IndustrialGrillCraftingSpeed=1.0
MeatSpoilerSlotCount=150
MeatSpoilerCraftingSpeed=1.0
MiniVaultSlotCount=600
BookShelfSlotCount=200
RareCollectorSlotCount=150
RareCollectorRange=15
TekRexSpawnWeight=5.0
TekParasaurSpawnWeight=5.0
TekRaptorSpawnWeight=5.0
TekStegoSpawnWeight=5.0

As for the settings themselves.
(Item)SlotCount refers to the inventory slots that the item has.. for eg, the Industrial forge has 150 items by default.

(Item)CraftingSpeed refers to how fast against default crafting (how fast in your inventory for eg) the item will take to make things. This is why the Replicator for eg, has a default of 12x. Because naturally the Replicator is 12x as fast as your inventory.

RareCollectorRange is the range (a radius of x foundations roughly) that the collector will pickup items in.

TekRexSpawnWeight.. this one is tricky. This controls the chance that a tek rex will spawn instead of a normal rex. Wildcard's defaults for this are 5% tekrex, 95% rex. This value can be changed from 5 to 95. It will default to 5, if the value is outside those parameters.