Use TLOGFONT structure for creating new font. For rotating text you must change lfEscapement and lfOrientation fields of this structure.

procedure TForm1.Button1Click(Sender: TObject);
var
  MyLogFont: TLogFont;
  MyFont: HFont;
begin
  FillChar(MyLogFont, Sizeof(MyLogFont), 0);
  with MyLogFont do
  begin
    lfHeight:=0;
    lfWidth:=0;
    lfEscapement:=StrToInt(Edit1.Text);
    lfOrientation:=StrToInt(Edit1.Text);
    lfWeight:=FW_NORMAL;
    lfItalic:=1;
    lfUnderline:=1;
    lfStrikeOut:=0;
    lfCharSet:=DEFAULT_CHARSET;
    lfOutPrecision:=OUT_DEFAULT_PRECIS;
    lfClipPrecision:=CLIP_DEFAULT_PRECIS;
    lfQuality:=DEFAULT_QUALITY;
    lfPitchAndFamily:=1;
  end;
  MyFont:=CreateFontIndirect(MyLogFont);
  Form1.Canvas.Font.Handle:=MyFont;
  Form1.Canvas.TextOut(100, 100, 'Hello');
end;

This example gets Form.Font width and height. Use TextWidth and TextHeight methods of TCanvas type.

procedure TForm1.Button1Click(Sender: TObject);
begin
  Label1.Caption:='Width is '+
    IntToStr(Form1.Canvas.TextWidth(Edit1.Text))+
    ' pixels';
  Label2.Caption:='Height is '+
    IntToStr(Form1.Canvas.TextHeight(Edit1.Text))+
    ' pixels';;
end;

SelAttributes.Style method of RichEditComponent. You may set bold, italic, underline, strikeout style and other parameters of font in RichEdit. And don't forget to return focus to RichEdit component.

procedure TForm1.Button1Click(Sender: TObject);
begin
  if fsBold in RichEdit1.SelAttributes.Style then
    RichEdit1.SelAttributes.Style:=
      RichEdit1.SelAttributes.Style-[fsBold]
  else
    RichEdit1.SelAttributes.Style:=
      RichEdit1.SelAttributes.Style+[fsBold];
  RichEdit1.SetFocus;
end;

All fonts you may get by using Fonts property of TScreen class.

procedure TForm1.Button1Click(Sender: TObject);
begin
  Memo1.Lines.Assign(Screen.Fonts);
end;