Hi,
1. You can change that here: https://i.imgur.com/Tm6kXkx.png
2. & 3. Unfortuantely these are not possible. The pagination is actually a great idea, I have added it to the issues tracker, it might be added sooner or later in a future release.
The number of products by checkboxes is a bit different story, it is intentionally not implemented (yet). Interestingly it is a huge perfrormance caveat to simply count the matching rows, because the query gets super complex. We are working on a complete filters UI rework, and this is on the list of future updates for sure. Many other plugins actually have this feature, but as soon as you have like 5000+ products, the performance of almost all of them fails miserably. We hope to find a way to overcome that issue.
