Oh just saw the date on the post, i will leave the comment though 😅.

1. As such yes, but it is also a question of the sensitivity, frequency response etc. of the drivers - this is a great resource for beginning a diy build: https://www.diyaudio.com/community/threads/so-you-want-to-design-your-own-speaker-from-scratch.332688/

2. Generally i would say no, as you get quite a bit of functionality for the money from surround receivers. But if you only want to use pc as a source, have a surround sound card/output, doesnt want more than 7.1 surround/atmos then sure. It also depends on your budget.