Custom Post form for Sharepoint 2016 Publishing Portal

Question

I am working on a Public Facing web site(Publishing Portal) using Sharepoint 2016. My requirement is to create a custom form which looks like below.

My Question is.
1) How to create a Custom Form for Publishing Portal in Sharepoint which is able to post data.
2) Will I be able to post data to Sharepoint List as a site user? If so How to achieve it?
3) How can I protect that particular list so that nobody is able to read data from it using a rest api.

Looking forward to your replies please.

Answer 1

Create farm solution with custom webpart(custom form you shared), demo.

Use SPSecurity.RunWithElevatedPrivileges in your webpart to maintain list data.

http://mekishordas.blogspot.com/2013/03/runwithelevatedprivileges-in-sharepoint.html

SPSecurity.RunWithElevatedPrivileges(delegate()  
    {  
        using (SPSite site = new SPSite(siteID))  
        {  
            using (SPWeb web = site.OpenWeb(webID))  
            {  
                // Code Using the SPWeb Object goes here  
            }  
        }  
    });

Set list permission to owner only(break list permission), others can't read it.