N150P3-L01 looks like a pretty good panel, and the price you got it for is excellent. At 116Pixels/Inch the pixel density is just slightly lower than that of a Cintiq 12WX, except being 15'' it gives you more room for drawing. 1600x1200 would've been your ideal case for that size and 4:3 ratio (they dont make 4:3 panels anymore), but the extra 17 Pixels/Inch wouldn't be worth it if you have to pay over 30$ to get it.
- You most definitely need IPS or VA - TN is garbage, especially for tablets. For any kind of graphics work, and also for a tool you will want to rotate and look at from all angles, consistent colors are a must. TN is only popular for being cheap and because the faster response times are sometimes more desired by gamers.
- On the subject of response times - they're more or less just a marketing buzzword to sell the product with. There are many ways that response time is measured (Grey to Grey, White to Grey, Black to Grey...) which are often different, and they usually advertise whatever number is lowest. Same goes for contrast ratios - they're normally about 500:1, but with some backlight modulation tricks you can sort of fake it and bump that to "100,000:1", and that's the number they slap on the bezels of new monitors and TVs.
- You might experience a little ghosting while playing games, but for drawing i doubt you'd notice anything.
And one last question : what is the difference between IPS and DD-IPS ?
There's hardly any difference, they're all IPS technology. Every manufacturer uses their own names for variations of the IPS tech. DD-IPS is IBM and IDTech's version, there's also e-IPS and S-IPS by LG, AFFS which is used in most TabletPC screens, p-IPS... There's a lot of them, you can read more about it HERE
if you're interested.