Is this app is cost less?

Absolutely yes! it is free to download as well as free to use.

Can I use it on IOS devices?

Some Mod design platforms are only for android mobiles.

Not really! The app didn't offers any hidden charges.

It totally depend upon the user how he use. But don't disobey its terms and services.

You can update it regularly to boost it functioning and to allow it to add new forms and features.