I’ve already detailed how to create a new Taxonomy Field in CSOM – here’s the more generic how to create a general field on a list.:

internal static void CreateFields(ClientContext clientContext, List targetList, string xmlDef)
{
 targetList.Fields.AddFieldAsXml(xmlDef, true, AddFieldOptions.AddFieldInternalNameHint);
 clientContext.ExecuteQuery();
}

And as a bonus, here’s how to set a field to be indexed in the client side object model:

internal static void SetIndex(ClientContext clientContext, List list, string fieldName)
{
	Field f = list.Fields.GetByInternalNameOrTitle(fieldName);
	clientContext.Load(f);
	clientContext.ExecuteQuery();
	f.Indexed = true;
	f.Update();
	list.Update();
	clientContext.ExecuteQuery();
}