Photoshop CS4 compatible with Windows 10?

If you move up to a new version of PS, your actions may require some editing.

Menu options and functions have changed since CS4 and will break in newer versions depending on the complexity of your actions.

There are no other versions of Photoshop you can buy without a subscription, unless you want to go the route of Photoshop Elements.

Do not buy any Photoshop except PSE - there are many scams out there and there is no guarantee of the validity of the license.

That being said - PS CS4 will defintely show some issues when you run on Win 10. You will need to reinstall the app after upgrading as resource file locations move with the upgrade. You will need your install disk or access to the installer from your account on Adobe.com

If you don't have either of these, you may be out of luck altogether. Adobe officially stopped supporting CS5 and back even with Activation issues.

It should probably work, but expect some issues and problems. Nobody can give you any guarantees. The world has moved on quite a bit since 2009.

As for actions, same thing.