1) ACF 5 Pro includes all add-ons, so there is nothing else to install. The add-ons are only need to be installed separately if you are using the free version.
2&3) No, there is not feature that will do this in ACF.
4) I use WP All Import for all imports because the pro version of that plugin has an add on that works with ACF.
You can add forms to the front end of the site using the acf_form() function. Details for using this are here https://www.advancedcustomfields.com/resources/acf_form/ with additional information here https://www.advancedcustomfields.com/resources/acf-pre_save_post/ and a tutorial here https://www.advancedcustomfields.com/resources/create-a-front-end-form/
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