KRC4 CMOS battery replacement

1. yes...

2. possibly.

3. of course.... be aware of ESD and use correct measures and do not touch what you don't have to. the official guide is to replace CMOS battery every 5 years and other batteries every 2.5 years.

in general:

static electricity is capable of destroying just about anything but the most sensitive are CMOS components. and you are replacing part that power CMOS RAM. touching CMOS devices that are not yet in the circuit will easily damage them but once the parts are soldered to board and surrounded by other components, risk of damage goes down significantly. touching metal chassis of PC while accessing battery is actually going to dissipate most of the static that may be on your hands. and when handling boards make sure you are not wearing any synthetic materials. do not move more than needed and do not rub anything. for example do not walk and definitely do not drag your feet. every motion is producing friction and increasing static voltage. dragging feet, rubbing elbow against desk or wall will produce significantly higher charge. just walking in place is actually bad. this is why ESD straps and ESD mats are recommended. while your body may collect some charge, at least hands (which are actually getting in contact with circuits or components) are pretty safe. and those ESD mats and straps are useless unless they are properly grounded. this means they are not to be connected to GND directly but through a high value resistor (usually 1MOhm is built in at one end of the wire). purpose of resistor is to allow equalizing of charge but limit current to safe levels.