Force charging-Charging even after reaching 100% in battery backup.
I guess you mean tickle-charging: Keeping the the charger attached, so the battery keeps being held at 100%. This is indeed not the best you can do to a Li-Ion Battery, but the manufacturer actually took care of this: 100% on the battery meter corresponds to ca. 80% of what's theoretically possible with Li-Ion batteries. There is a trade-off between capacity and longevity.
Charging only after the battery empty.
It's common that people believe that full-cycling (charging only when empty and then completely) batteries extends their lifetime. While this is is true for Nickel-based batteries, all modern laptop batteries as Li-Ion. Full-cycling is the worst you can do to such a battery, because they hate both being empty, and being full. They last longest when kept half-charged. However, it's recommended to full-cycle the battery once in 6 months to re-calibrate the battery meter since the capacity decreases over time and readings may become incorrect.
Charging parallel while working.
Charging while working is no different to the battery from just being charged electrically. But the heat caused by the Laptop adds to the heat from charging. Heat is what Li-Ion batteries hate most. It will reduce their lifetime. However, if the Battery is thermally well seperated, this should not be a problem.