Welcome.
1. Its neccesary to oil and grease your AEG once in a while to make sure everything keeps moving smoothly. If your skilled in working on the inside of a mechbox, you can pick up a G&P grease kit for cheap and use that.
http://www.airsoftparts.ca/store2/in...roducts_id=414
Some people have recommended that occasionally shooting a squirt of silicone oil down the feeding hold in the magwell helps, I cannot comfirm or deny this. Personally I see silicone oil as more of a gas gun maintenance item.
However only a certain kinds of silicone oils can be used, those without petroleum distillates, as those have been found to be harmless to seals and other parts of the mechbox.
2. Gears require a small amount of grease.
Piston grooves in the mechbox, and I like to use a small amount of cylinder oil inside the cylinder.
3. Different bb weights will effect penetration through things like bush and brush when your playing outdoors. The higher weight will decrease your FPS and distance overall but will aid with getting the BBs through things like dense leaves. Im assuming your gun is a stock gun, I would recommend either .20g or .25g BBs.
Upgrades should be left up to someone who has the knowledge to work with a mechbox, if you are comfturble with attempting this yourself you can check out websites like mechbox.com and see if you can find information to help.There is a wide variety of upgrades out there, from internal to external parts, what to get is based on what you want to upgrade. As I stated before, mechbox upgrades and repairs are not an easy thing to do, but there are a few airsoft gunsmiths in the bc area that should be able to assist you with anything you may require.
Your in BC, your in good hands in that province as there are alot of players out there.
I believe this is the forum for BC.
http://www.bcairsoft.com/