Microcontroller's JTAG interface and PCB
When you add a JTAG port to your PCB, you can use the JTAG to debug your software while the microcontroller is on your PCB. This is a huge advantage and will speed up debugging.

The choise between between DIP and SMD depends on your soldering skills. If you are able to solder SMD, choose SMD. It's smaller and there are more different microcontrollers available with a SMD package.