Pad chargers are mainly of two types as follows.

Apple iPad charger: These are Apple’s proprietary chargers designed for its own devices. As a result, they are usually the most compatible ones.

Third-party charger: Some reputable universal third-party chargers are also compatible with iPads via USB-C cables or Lightning to USB-C cables. Compared to Apple chargers, these chargers sometimes have greater charging capability, like the Anker 747 charger which boasts an impressive 150W output and simultaneous charging for 4 devices.

Yes, it is generally okay to use a non-Apple charger for your iPad, as long as the iPad charger port is Type-C and the charger comes from a reputable brand like Anker. These third-party chargers may be specifically designed to be compatible with Apple devices, including iPads, and often meet the necessary safety and performance standards.

There should not be any problem if you use your cabled iPhone charger to charge your iPad as long as their ports match. In fact, most latest USB-C chargers, including Apple’s original ones and third-party chargers, are simultaneously compatible with a wide variety of Apple devices like the iPhone, iPad, Apple Watch, etc. However, if you want to charge your iPad with wireless chargers for iPhone, you’ll fail because iPads do not support wireless charging.

At least 5V is usually needed to effectively charge an iPad. This is because iPad models typically require a wattage of 10W and a current of 2A to charge properly. Divide 10W by 2A, and you’ll get 5V, which is the required voltage.

No, it's not necessary to charge your iPad to 100%. Modern devices like the iPad use lithium-ion batteries, which perform best when kept at a partial charge. Charging to around 80-90% and avoiding complete discharge is recommended to maintain battery health and prolong its overall lifespan.