1) Adjust the fields, then combine the values and submit as ajax as an HTTP POST, and display a thank you message.
2) Make a short interview-type contact form with simple toggle answers. Then, depending on the replies (I will provide the logic), bundle the answers into an HTTP form POST, and display a thank you message.
You would edit the HTML/CSS/JS, and the revision will be similar to the bottom interview like the the this: http://bit.ly/2pLSCNZ (See "the the Add Your rating of this of the this" "Did you call the the this number?). After the short interview, as above, for certain replies (i.e. certain answers), combine the data and submit via an HTTP POST to an existing ajax script.
Some unix expertise and a public ssh key required.
Got several questions:
1) Is it necessery to send ajax if user don't answered "yes" in one of that steps?
2) Can I just put your logic written on native javasript into html-pages? Or you are using some frameworks such Angular/React?
3) Where would you like to send user's answers? They will be processed by server or you just want to get them on your e-mail?
Here my form written on jQuery sends ajax on PHP-server-sided-scipt, which takes that data and sends it by e-mail: http://hvn-magnet.com/price4.htm