Lead Developer
Hi there,
1. This plugin may be helpful: https://wordpress.org/plugins/say-what/
You can target the email placeholder (Email *) and add your own text.
2. Same as above – use the plugin to search and replace the text strings.
3. This plugin should work: https://wordpress.org/plugins/subscribe-to-comments-reloaded/
4. Give this plugin a try: https://wordpress.org/plugins/wysija-newsletters/