1| It can't be overcharged since the circuitry within your laptop will automatically stop charging the battery when it reaches 100%.
2| It will only explode when subjected to manhandling or if you decided to open the battery for no apparent reason.
3| You may want to keep an eye on the temperatures for your laptop since high temps can degrade your hardware's longevity+the cooler will clog up with dust/debris.
4| Ideally, you should discharge the laptop's battery once it's fully charged to 10%(by using it off the battery and not connecting to the wall socket). That should ensure that your battery is optimally performing. Once drained to 10%, charge back up to 100%, using the laptop for gaming during charging isn't going to be an issue.