Hello Jitendra Mandalia,
1) This is not possible out-of-the-box. We are planning to have "custom grid line"
2) This is also not possible out-of-the-box, however, you can approximate it using line series. You can check this example
to see how to disable labels and point-marks for line series.
3) You can read here
how to change the theme of the control. Here
you can read how to further customize the default theme of RadChart.
4) You might want to review this blog post
the Telerik team