Make sure you do not try to use the MCLR pin as an input and use the Internal Oscilator at the same time This does not work for some reason and can make chips useless.
Somebody forgot to tell my 12F675 parts because they all work great in this mode. It appears nobody has told microchip either

1) Modifyit is right - WDT is good to stop lockups. Because PBP normally does not know if you will set the WDT fuse or not, the code length is the same regardless. If you do not plan to use the WDT and are really squeezed for space, you can insert

DEFINE NO_CLRWDT 1

at the beginning of your code for a very modest savings in code space. If you are planning to use sleep commands (which you said you are not), it is better to use the WDT (if you want them to work).

2)
If I set MCLR internal do I need 10k resistor?
No - there is not one in place if you program in the PSP ZIF, not one needed for ICSP. You probably need the diode as suggested my modifyit - it depends on your circuit.

3) If you set the fuse for Power up timer, you are using it (you have no choice with the fuse set). Setting this bit keeps the processor in reset for 72 mS at power up - see datasheet. I like mine on but it depends on what you are doing.

Paul Borgmeier
Salt Lake City, Utah
USA