When creating a new email template, I'd like to modify the Type Selector dropdown and add additional selections in there. From what I see I need to do a few steps, can anyone confirm/deny these steps and what else I might need to do or not do or if this is even a good idea.

1. Add additional Enum items in App_Code\CMSModules\Macros\EmailTemplateMacros.cs
2. Modify GetEmailTypeEnum(string emailType) in file above and add new case lines.
3. Modify GetEmailTypeString(EmailType emailType) in file above and add new case lines.
3. Create a new ContextResolver in above file.
4. Modify GetEmailTemplateResolver(EmailType type) in above file and add new case lines.
5. Add additional Resource strings in CMSResources\CMS.resx (or can I do this in Site Manager>Development>UI Cultures?).

Then when I create a new email with a template using the API, will I still need to resolve the macros like so?

MacroResolver mcr = new MacroResolver();
mcr.SpecialMacros = new String[,] { { "##one##", "1" }, { "##two##", "2" } }; 

Or will they be resolved with the steps I've completed above?