From what I have seen it only uses the 5 pins vdd vss mclr for the 12f gp0 gp1 or the 16f rb6 rb7 and some circuits I have to use jumper to Isolate mclr
The pickit2 brings the chip to vdd to read after programing and turns it back off
and if i use mplab it stays at vdd after programing. I have also had to isolate rb6 and rb7 on a 16f84a or remove the LCD I had hooked to It.
Another consideration with MCLR/VPP is that when the PICmicro device is programmed, this pin
is driven to approximately 13V and also to ground. Therefore, the application circuit must be isolated
from this voltage provided by the programmer
During programming the other pins are inputs and so high Z. I have had the problem of external circuitry floating high during programming and have had to fit temporary pull up/downs to prevent this.