Is this a good design of a testable knockout and typescript project?

I'm working on a project that will grow very fast and I am trying to build it with TDD in mind - that concept that everyone uses, but few of them are actually implementing it. As frontend technologies KnockoutJS and Typescript were the winners and both are almost new to me, but I got the idea behind them.

For the moment I am building up the boilerplate and I am stuck in my freaking and annoying ideas about how to do this properly. Before I've used AngularJS and things were a bit different. And, because I am coming from the magic world of angular framework, I would also like to include some kind of $injector in this project.

So, to stop the story, this is what I have in mind ( notes & explanations below each code section )

Model

module Models
{
    export class Person
    {
       //code for person
    }
}

I dont' think I need anything fancy for models. Maybe a BaseModel that should be extend by the rest, but that should be discover while the project is growing.

So, my first question:

Q1: Do you treat your models in a different way, or you see them as simple POCO(POJO) objects ?

ViewModel

module ViewModels
{ 
    export class PersonViewModel extends Editable
    {
        @inject('PersonRepository')
        personService:PersonRepository

        // stuff specific for current view model
    }
}

As you can see, here are few concepts I would like to use.

First of all that base class for view models Editable, which is used for Editor pattern ( link provided )

Second, @inject decorator is used for DI, to inject repositories in view models ( somehow similar with injecting angular services into controllers, at least the logic, not the implementation )

Third, I added another layer, the Repository layer. I've added this for testing purposes, to separate some concerns that should stay in a service and not in a view model.

Q2: Should I use a BaseViewModel which will implement Editable ( this would contain stuff like sorting, filtering, at least, this is what I have in mind right now ). If so, what do you usually do in your BaseViewModel class?

Repository

module Repository
{
    export class PersonRepository
    {
        // repo stuff
    }
}

Question nr 3:

Q3: Is there any reason to add a BaseRepository in a knockout application ? Did you do/ are you doing something like that ? Because I see no reason to add one.

Q4: Should I return a Promise or use callbacks for server side calls ? I think promises is a more elegant way to do it.

Q5: Repositories will be mainly used for server side calls and for performing logic needed for view model. It's ok ?

View

No explanations here

Please note I want DI to decouple some things and make them more testable ( for example I can inject a fake repository in tests ).

Any advice is appreciated. Thank you !