#1 I leave my microwave oven door open, so is the light bulb easily accessible to be replaced?
I think all you have to do is take off the cover to access the bulb.
#2 Has anyone had a problem where the key pad is too dark/not illuminated?
No problem with illumination, but BIG problem with keypad lettering not lining up with where the button actually was. Some buttons on lettering wouldn't function at all. Returned to get my money back for that reason.
#3 My husband likes to cook 3 or 4 bags of popcorn one right after another but microwave started sparking after the third bag. What did we do wrong?
This is not a question for a purchaser .It needs the attention of the tech team atToshiba.
Press cook time. Enter 15 seconds. Press start. If you need to change power level press power level then start. For warming something up 30seconds just press start. I hope this is helpful.