winaltdell

No, cause you do it manually, 100 submission is not spammy and you are not sure that all directory sites approve your links.

Doing link building techniques such as bookmarking, directory submission, article submission, forum and other ethical ways to spread your site link is helpful to increase your link popularity and ranking.

Yeah! Keyword stuffing is a unethical seo technique. Keyword stuffing means overusing a keyword to increase the keyword density on a page.

In my opinion, Google read your backlinks weather it is do follow or no follow, However, Google hide most of your backlinks and show few backlinks from authority sites to protect your site from Seo that spying your backlinks

In my opinion, using 1 database for multiple website is not applicable and it can cause duplicate content/data issue.

In my opinion, it doesn't matter if your url has https or in default http. Both url are search engine friendly. The only difference between https and http is the security. https is more secure than http cause https cause it is encrypted by SSL Certificate.