UIViewController and PushAsync with DasterDetailPage

I'm creating a project that follows this excellent menu structure

https://github.com/jamesmontemagno/Hanselman.Forms

Using this structure could easily adapt my application, however run into two issues,

1º Issue:

I would like to open a UIViewController when you click the menu.

The menu only works with pages and in a particular option would open a UIViewController is possible?

case MenuType.MyPosition:
                    if (pMyPosition == null)
                        pMyPosition =  new Pages.CrossMap(_DB);

                    PageSelection = pMap;

2º Issue
So that navigation works, keeping the menu, I need to trigger the call Page by own menu

When I try to open a page by another page the menu disappears, or appears a back button.

new System.Threading.Thread(new System.Threading.ThreadStart(() => {
                Common.Syncronization Sync = new Common.Syncronization (_db);
                Sync.StartSync();

                Device.BeginInvokeOnMainThread (() => {
                    Status.IsVisible = false;
                    Label.Text = "Syncronization Complete";
                    Label.TextColor = Color.Green;
                    this.Navigation.PushAsync(new Pages.Cross(_db));
                    this.Navigation.RemovePage(this);
                });
            })).Start();

Can anyone help me with these problems?