I think the second domain Bonusspins.com is better for SEO. Visitors might think that there is a spelling mistake in your domain if you use the first one
I think it depends. If the content of the paid site mentions something relevant to your content, Google will consider it a good backlink. However, you should consider the ROI.
I used to use both of them. Each tool proves useful in their own way, depending on your purpose. I often use SEMrush for traffic organic analysis, keyword research, and site audit while Ahreft helps me in backlink building.
If I must choose one out of the 2 tools, I would love to pick SEMrush...
It's not 100% right to think that it's bad to have many pages from the same domain rank for a particular keyword. Actually, Google is smart. It always understands what your pages are about and whether they match the reader's search intention.
However, there are a couple of reasons you may want...
I think it's quite long but not too long. You might find it a little bit difficult to optimize your blog's URLs in the future. However, if your domain already includes important keywords, it's great.