Retrieve fields, fields type, fields values and column names of a Sharepoint Content Type used in a library using Javascript

I created a library that contains documents in Sharepoint Online. Let's call it myLib. I also created a content type, myCT. My objective is to retrieve informations concerning fields I created in a content type in sharepoint online. The library is using the content type i created.

For this i also created a webpart component that aims to generate a form with the content type fields / columns. I need to retrieve :

• the field name
• the field type
• the values (for select, radio buttons, checkboxes)

For this I found that i can access XML datas from sharepoint at this URI : https://myAppUrl.sharepoint.com/_api/web/

My issue is that I spent a rather long time trying to find where the data from the content type is stored. I tried those URLs :

• https://myAppUrl.sharepoint.com/_api/Web/ContentTypes
• https://myAppUrl.sharepoint.com/_api/Web/AvailableContentTypes

Without finding what i'm looking for. I also tried to create a script in the webpart: :

function getallContentTypes() {
    var clientContext = SP.ClientContext.get_current();
    oContentTypes = clientContext.get_web().get_contentTypes();
    clientContext.load(oContentTypes);
    clientContext.executeQueryAsync(
        Function.createDelegate(this, function() {
            var ctypesInfo = '';
            var ctypesEnumerator = oContentTypes.getEnumerator();

            while (ctypesEnumerator.moveNext()) {
                var ocontentType = ctypesEnumerator.get_current();
                ctypesInfo += '\n' + 'ContentType Title: ' + ocontentType.get_name()+'\t'+ ocontentType.get_id();
            }
            console.log(ctypesInfo.toString());
        }),
        Function.createDelegate(this, function() {
            console.log('failed');
        }));
}

function injectMethod(){
    getallContentTypes();
}
ExecuteOrDelayUntilScriptLoaded(injectMethod, "sp.js");

it returned me information concerning the content type : ContentType Title: myCT 0x0101007D18D0E5D0A176498869E2673AD0CA14

Now i wish to know how to handle this.

UPDATE after FredericDietrich help : I tried to use URL like : _api/Web/ContentTypes?$select=Name,Id,StringId&$filter=Name eq 'myCT'

And i obtain an XML:

<feed xmlns="http://www.w3.org/2005/Atom" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:georss="http://www.georss.org/georss" xmlns:gml="http://www.opengis.net/gml" xml:base="https://dsidiff365.sharepoint.com/_api/">
    <id>c2f25390-1496-45f6-9c87-0f6c0a9ea026</id>
    <title />
    <updated>2019-11-27T15:54:07Z</updated>
    <entry>                <id>https://myurl.sharepoint.com/_api/Web/ContentTypes('0x010100ED0CEB986D733A47AD45D9A995911BAA')</id>
        <category term="SP.ContentType" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" />
        <link rel="edit" href="Web/ContentTypes('0x010100ED0CEB986D733A47AD45D9A995911BAA')" />
        <title />
        <updated>2019-11-27T15:54:07Z</updated>
        <author>
            <name />
        </author>
        <content type="application/xml">
            <m:properties>
                <d:Id m:type="SP.ContentTypeId">
                <d:Name>Facture</d:Name>
                <d:StringId>0x010100ED0CEB986D733A47AD45D9A995911BAA</d:StringId>
            </m:properties>
        </content>
    </entry>
</feed>

but no information concerning fields