You were pointed to a valid solution and you don't want to use it because it uses API hits. And API hits generally require a donation, the fact that you want to avoid the donation and still automate the search is a problem.
Not at all, but you're a valid visitor, probably being served an ad, which does give the site some revenue, if ads are being served to programs fetching things without a user seeing them it defeats the purpose and could have a negative impact on the site.
Is that not what NZBHydra provides? Yes it uses API calls, but you probably don't need 100 indexers that generally have the same thing. A few good indexers, with reasonable limits and grabs per day is plenty from my experience.
They don't use an API on the trackers though, they just expose an API so Sonarr and other apps can access it.
Indexers aren't going to want that though, they can and would shut it down, like they have with apps using their API being too abusive.
Anyways, this isn't the place and is off topic at best. Good luck.