The “show form” component is designed to show a form, not a new tab. A form offers some components like columns, special values that a tab doesn’t offer.
You almost have it right. So a form button can be placed on any page and then be fed into any sheet, you choose. The values you can feed from depend on where the form was launched from and the type of components being used (the choice can use data from anywhere as it is expected your choices will reside somewhere else for instance)
Create the form button and choose what sheet it will feed into. Click the form button you made to open and configure the form.
To capture the users email without the user needing to put it in, there is a special field type (shown in forms only) called columns. This will allow you to pull data from the originating sheet and push it into one of the form’s submission tabs without user interaction.
The submit button is built into form either a submit or a checkmark for iOS and Android respectively located in the top tight corner of the form. You cannot add a separate form submit button.
You cannot automatically show a form. It requires a user to click a show form button. The only way around this would be to build a form yourself from scratch which will not function as the above and will be much more involved.