Is there a way to increase the spawn rate of monsters and such?
If you mean a specific monster, give it a larger share of the spawn tables at the top of reverieAI.cs. If you mean monsters in general, change this line (line 338) in the same file:
%interval = getRandom(70, 120) * 500;
This corresponds to an NPC spawn interval of between 70/2=35 and 120/2=60 seconds. Lowering these numbers will increase the overall spawn rate.