Yes, it's worth paying attention to these questions as they are very important. If renetion is mostly related to compliance requirements of the industry. Some data should be kept for 5 years and some for 20, so it's good if a backup solution provides long-term or unlimited retention.

Regarding the cost, I think that a backup solution is always much cheaper than the cost of data loss. So it's better to have a backup than not.

And, of course, restore and recovery checks are also important. Moreover, a backup solution should foresee different disaster scenarios. for example, disaster scenarios like those described here in the article: https://gitprotect.io/blog/github-restore-and-github-disaste...