We are not.
We do not. Your best chance to purchase our assets at a reduced price is to do so when they get selected for a sale.
Please refer to the asset's page on the Asset Store, which includes a complete description of the features included, a link to the complete online documentation, a gameplay trailer, many screenshots and (in many cases) a complete playable web demo. You can safely assume if a feature is not mentioned in any of these resources, it is not included in the asset and would therefore need to be implemented on your end.
Unfortunately, we cannot answer that. How easy something would be to implement will ultimately depend on your skills, your familiarity with C# programming in Unity and your willingness to dive into a third-party codebase.
We consider our assets to be a complete starting point already, so probably not. While we are open to your suggestions, we cannot promise they will be incorporated into the asset in the future. Your idea might be very useful to you, but not necessarily to everyone else (it might be too specific, might excessively complicate the asset, etc.). We always recommend buying our assets based on the features they already provide.
We are always happy to help with issues or bugs in the default assets as they are sold and without any custom changes. We do not provide support for general Unity questions or for custom features not included in the assets (please refer to the official Unity documentation and the many tutorials available from other sources for these). If you have found a bug in one of our assets, please make sure to send us a valid invoice number for your purchase, your Unity version and the complete reproduction steps to reproduce the issue on the latest version of the asset without any custom changes.
All of our assets are governed by the Asset Store EULA. This means you can only use them for the development of your own, final games.
No, they cannot. All of our assets are licensed under the Asset Store EULA, which means you can only use them for the development of your own, final games. They cannot be redistributed or resold in any way; not even if re-skinned, not even if providing a part of their contents, not even if only providing a final package to be uploaded to a store (.APK or similar). Please do not support piracy websites, sketchy resellers or hosting companies that allow these to exist in the first place that try to illegally profit from the hard work of small studios creating original content.
We do not. If you find any of our assets being redistributed or resold in any other websites, please report the situation to us so we can take the appropriate actions. Thank you for supporting us!