Some of the theme features don’t work or give errors, why?

What can cause the problem:

Magento cache (or external cache) was not flushed after installation of the theme.

Compilation mode was not disabled before installation.

Some of the theme files were not uploaded.

You edited theme files and accidentally removed or changed something in the files.

You have customized the theme by creating custom sub-theme and your modifications change/break the default behavior of the theme.

Sometimes you have installed other theme and some elements are currently affecting the current theme.

Can I change current theme color store wise?

Yes. You can easily change your theme color from Theme Cpanel > Theme Design > Design Settings >Theme Color.

How can I select other home page for my store?

You can select other home page from Store > Configuration > General > Web, select your home page from CMS Home Page.

Some images are missing or not displayed (e.g. in the spdeshow).

This may be file permissions issue, or your Magento does not have access to images because of incorrect file permissions on your server.
First, make sure that images were uploaded and if correct paths to those files are specified. You need to set correct file permissions for all images and folders (in most cases images are stored in pub/media directory).

Do not appear theme configuration changes on the frontend.

Flush Magento cache in System > Cache Management, clear web browser cache/cookies for your store domain and refresh the page in your web browser.

One of my extensions does not work with this theme.

Generally all extensions can work with all themes but sometimes they have to be integrated manually. That is because sometimes the extension and the theme override the same Magento template file so there can be a confpct.

From where, I completely disabled extensions that comes with theme.

You can completely disabled extensions from Store > Configuration > Advanced > Advanced