Can I use fast chargers and power banks for iPads? Do they affect in any negative way?

What exact model iPad do you own? Depending on whether your iPad is fast charge capable, giving it a charge from a higher wattage charger will only charge it the fastest your iPad is designed to be charged. Otherwise, a higher output charger won't harm the iPad as long as the charger is appropriate for an iPad.

The iPad comes with a 20w charger in the box. It will charge the iPad as fast as its designed to charge. Using a higher wattage charger, will not charge the iPad any faster. But it won't harm it either.

You're welcome.