That's right.2. Can you safely revmoe the hardware? ('the' is in here, does this mean it is known to me and the listener?)
Both 3. and 4. are fine. 'the' is often omitted in instructions--saves time and space.
6. I observed the life of a drug dealer. (Everyone knows what ‘life’ is, so ‘the’ is correct and ‘a’ is not right? What's 'the' referring to?)
The rest are too odd.