alright.. jumping from the 18t freewheel to a 17t (im a big boy now)

i got the freewheel tool. any tips on doing this? lay the rim flat on the ground , brace, and start applying torque? wouldnt it put a lot of stress on the spokes and hubs ? im not sure... about to break the cherry here....

after threading in new freewheel... torque down or just ride it out tight?

That'll work or try this...
Stand the wheel up, apply the freewheel removal tool and then secure it, but not too tight, with your QR lever. then take a long pipe and stick your ratchet or wrench in the end of it and use the pipe to apply leverage to remove your freewheel. Don't forget about the QR and take it off before completely unthreading the freewheel. Or you could stick the freewheel in a vise and then turn the wheel like a bus driver turns his steering wheel, basically using the wheel as the wrench.

Use your quick release or axle nut to hold the freewheel removal tool snug up against the notches in the freewheel. This will help prevent slippage. Then, stand the wheel upright and brace the outside of the tire (this method assumes the tire is mounted) against a wall in such a way that when you turn the wrench handle, the tire will be pressed against the wall. This keeps the wheel stressed in a way that it was built to handle. Haul away on the wrench handle, and the freewheel should loosen pretty easily if the threads were properly greased when it was installed. Once you've loosened the freewheel, remove the axle nut or quick release and it should unscrew by hand.

To install the new freewheel, just tighten it hand-tight so it's snug, but be careful not to cross-thread it. The first few turns of the cranks should torque it down just right. Don't forget to grease the new threads before installation.

Cheers!

ah... yes... lube... almost forgot. will lithium grease do?

It'll do just fine. The purpose of the grease is to prevent corrosion and thread seizing, so anything that works to those ends is sufficient.

I like putting the remover in a vise. This allows you to turn the wheel like you're steering a ship with two hands.

cool, put the b*tch on a vise bench to took it off... i was initially wary because it felt like it needed the Jedi Force to come loose

anyways... now im out of lube/grease! can i use motor oil or wd-40? (its antiseizing / anticorrosion)

Do it right and use grease... You want something that won't have bled out of the threads 10 years down the line when you want to sawp out for another freewheel. Take the time, wait for the hardware store or LBS to open tomorrow and go there to get some proper grease.

Open beer. Unthread freewheel, typically counter-clockwise. Replace with fixed cog. Open second beer. Ride.

"I like putting the remover in a vise. This allows you to turn the wheel like you're steering a ship with two hands."

diditto