To Example 2:

I tried it and no change in look, all display OK. When you will demonstrate me wrong look, please send me your picture with good and bad picture.
I tried it with some set up of TextureFileter() like

Code:
DXDraw.TextureFilter(Ord(D2D_POINT));
or

Code:
DXDraw.TextureFilter(Ord(D2D_LINEAR));
and no bad look give.

Via your code like
Code:
procedure TMainFm.DXTimer1Timer(Sender: TObject; LagCount: Integer);
begin
  DXInput1.Update;

  if not DXDraw.CanDraw then Exit;

  DXDraw.BeginScene;
  {D2D_POINT, D2D_LINEAR, D2D_FLATCUBIC, D2D_GAUSSIANCUBIC, D2D_ANISOTROPIC}
  DXDraw.TextureFilter(Ord(D2D_POINT));

.......
To Example 3:

In DXDraws unit is texture limit like

Code:
const
  maxTexBlock = 2048;
  maxVideoBlockSize = 2048;
When you want use larger texture (in Px) please change this value (2048) or restrucuralize your to this size (size 2048x2048) without change value.

It is own limitation of DXDraws resp. DelphiX and I it put from code to public constant only.