I have my vent lint to the charcoal canister not connected to the engine block.

Would this create a vacuum leak? I dont know if that hole needs to be connected to prevent a vacuum leak if theres any present at the hole on the block.

 

Won't it heat the fuel up a bit?

 

I don't know about it causing a vacuum leak, but that hose is part of the system that keeps the crankcase gases vented. You may end up with condensation in your oil filler tube as a result.