The second is about Bitcoin mining; what is the difference between investing in bitcoin and mining bitcoin, or are they interchangeable? If you do not wish to purchase, will you mine your own Bitcoin?
Please accept my apologies if the question appears unclear; I am very confused, which is why I ask. Thank you very much.
You just proffered your answer, which is that you can just buy bitcoin if you don't want to mine it. Even while mining deals with the complexities of solving a puzzle in order to mine the next bitcoin faster than others, the costs associated with buying a mining machine make it difficult for many people to become miners.
When you buy a bitcoin from someone who already has one in his wallet, he can simply send it to you, making you a new owner of the bitcoin. Majority of people than own bitcoin today are not miners because of the difficulty and expenses involved in running a node of your own with much electrical energy consumption.