If you are looking for brushes and other resources you will find in this posting links to various brushes and other stuff, if you want to try them all you will probably be busy for months.
Since you specifically mentioned textures as well, at Texturize and at World-of-Resource you can find galleries of textures and, if you sign up there, download them as well.
Keep in mind that not every file format can be read by Krita, for example the Photoshop pattern format PAT cannot be read by Krita, thus causing confusion, as the GIMP pattern format, which is also called PAT, can be used by Krita. You can clarify this by looking into these files with an editor, in Photoshop you will find the string “8BPT” among the first characters at the beginning of the file, whereas in the GIMP patterns there is a “GPAT” written a bit further in the file.
If you are looking for further resources, you will surely find help here in the forum, in case of doubt I will probably be able to help you as well when it comes to sources for resources.
Michelist