Wordpress Cost Calculator plugin

Goal is to have a simple yet effective Wordpress Cost Calculator plugin to give users an easy and straightforward way to calculate costs (quotes).
It will have essential features including calculations, but no Wordpress user accounts or payment options.

The plugin will not be connected to the Wordpress database, except to store configuration values as required. Instead, it will be driven by plugin configuration using values for key variables, and a range of input files, such as form script and a html quote output. For added simplicity, the user won't be given the option to customise their calculations.

This quote calculator should be inserted into content, ideally via a shortcode.

The plugin will include a configuration file, and 2 other template files, (a php form, & a quote output template).

Part A - Configuration
The configuration will include values for use with the calculation formula.
The configuration will allow values to be set for rates, based on duration, early start/late finish, max radius distance
Quote layout can be configured in the configuration.

Part B - Form
The form will be created using a simple template php form (site editable file to contain form php code, so can be edited in future for improved layout)
The simple form will contain user's name, email, first 3-4 characters of postcode e.g. NN7 or AB12, which will be captured as 'shortcode variables' (to use in the quote layout, the webhook URL etc.)
5 calculation variables to consider
Start Date, Start Time, End Date, End Time, Max radius (miles)
Only start and end date are compulsory. Others are optional.
Pull Form template from Form template file in plugin folder in php format with placeholders using variable shortcodes

Part C - Calculation/Formula
This will run a conditional formula based on duration & time, using values from the configuration, coupled with data entered into the form.
This will calculate a quote, with max distance, showing a broken down price with & without this.

Part D - Quote
On submit, it will:
1. Pull Quote template from Quote template file in plugin folder in html format with placeholders using shortcodes
2. Calculate the correct quote, and display elements
3. Display granular quote in popup window or on the same page (Ajax auto-refresh)
4. Email displayed quote to user's email address with user's name + quote information
5. Bcc send quote information to 'internal' email address (bcc of quote to user)
6. Trigger webhook to opens custom generated URL link iwith webhook url (to add to a target (CRM) platform to record quote requests)

Part E - Variables
Captured Values:
name (Compulsory) {{name}}
email (Compulsory) {{email}}
Start Date (Compulsory) {{start_date}}
Start Time (Optional. If blank - assume = default) {{start_time}}
End Date (Compulsory) {{end_date}}
End Time (Optional. If blank - assume = default) {{end_time}}
Max radius (miles) - (Optional. If blank - assume = default) {{max_distance}}

Configuration Variables/Values:
RateA - £ {{RateA}}
RateB - £ {{RateB}}
RateC - £ {{RateC}}
EarlyStartFee - £
LateStartFee - £
Rate1PremiumDates - Table
Rate2PremiumDates - Table
MileageRate - £
internal_email {{internal_email}}

Webhook format:
Webhook TargetURL site is a value set in the configuration {{TargetURL}}
Webhook URL is a custom concatenation of text and shortcodes {{webhook_link}}
Webhook / API keys as needed

Email & Values:
Email subject line is a formula based on concatenating values/variables. This is to be created in the Configuration.
Webhook is a formula based on concatenating values/variables. This is to be created in the Configuration.