easiest way is to leave the chain on, put bike in gear then get someone to hold the rear brake on while you loosen the nut
There is a special tool ( a puller ) to remove the crankshaft sprocket.There is a special tool ( a puller ) to remove the crankshaft sprocket.
removing them, no, installing them, yes
After you remove everything required to get to it, it takes a special tool to pull it off the crankshaft.
De-soldering gun is used for removing molten solder, defective components, altering, and salvaging high value components in a circuit for possible re-use.
shearing
You can't put one sprocket on top of another, you have to remove what's there and then install another one. Depending on how much you change in size, you may have to adjust the length of the chain too. There are a couple of different versions of how the sprocket attaches, so make sure to figure out which one you need before you go and buy anything. Removal/assembly may require special tools, so it might be best to bring the bike to a shop.
Nothing special about that bike, go to www.sheldonbrown.com or www.parktool.com for explanations and maintenance instructions.
oversight
The fan clutch on a 1997 S10 has a bolt on the center of the front. Remove the bolt while holding the clutch still. There is a special tool to grab the clutch fan from the rear to hold it while removing the bolt.
Special characters are found by holding down the shift key above the numbers.
The pump is in the tank so get as much fuel out as possible then drop the tank after removing the hoses and wires. Use a special tool to remove the sending unit and pump assy.
It is located on the left (drivers) side of the engine near the back. It is located on the engine side of the head. You may have to move the throttle cables to get to it and I believe that the bolt holding it is a 8mm. Removing the bolt is not fun and will take some time and patience (small hands will help). Before removing the sensor you need to remove the uppermost cam bolt. If not it will prevent you from removing the sensor or possible damaging the new one. The bolt slightly penetrates the hole for the sensor. Take special care disconnecting the old sensor from the harness as this can prove difficult, they don't give you much to work with and the wires will pull out of the plug (I know).