The safest way of doing this is to strip your gun down and start replacing stuff. Adding high quality items like reservoirs lubricants, seals, valves, etc etc will give you a huge increase in power. If you feel like risking it though you can try (if you have a PCP or CO2 gun) rigging the release valve to only let higher pressure through, or modify the connecting outlet to allow for a bigger tank (that only works if the gun does not have a specific power setting, and instead just opens the valve for a set amount of time).
Keep it clean and get a stronger spring.
NO
No
you dont
Yes. A&K and one other company make an airsoft gun based on the design of the Magpul Masada.
At your house LOL.
I would highly recommend that you do not make your own airsoft pellets. They might jam and or brake your gun.
Because you, my friend, have a broken airsoft gun.
no. Airsoft guns could not possibly shoot that fast.
An Airsoft gun
The more powerful the batter just means the longer your gun will last before it has to be recharged. 'Fox Airsoft Store' offers some gun upgrades, these will improve your gun. Also, a gun's fps is already pre-determined by what parts are installed, upgrades will improve the gun but stronger batteries will only extend the gun's life before it needs to be charged.
Not worth it. You may damage your gun