It is a personal choice but you can use either. As a published author, I would highly recommend using a PC. Many agents now require an 'electronic' copy of your manuscript, as do publishers. Even if you are going to self-publish, you will still need to get it into a computer in order for any modern printer to handle the printing request. In the long run, it will cut down on costs and headaches.
Also if you make a mistake on typewriter... Big mistake. And PC are easier in my opinion
Citing for online anonymous authors
Yes, you can use the information, but you must cite the source website address.
It does not matter whether other writers enjoy writing! If you want to write, get started!