Hi Iris,
Sorry for the frustration. Some of this can be a little hard to grasp at first. And in truth, it may be this isn't the right product for you - especially if you're not finding value.
Regardless, let me go over these issues one at a time.
1. Canonical - This simply means you have a canonical tag on the page. It's not a high priority, or even a medium or low priority issue. It's simply a notice so that you know it's there (in case it's not suppose to be).
In this case it looks like the tag exist as it should, so there's nothing to worry about.
2. http://villasdiani.com/?db
If you click that link you can see the page resolves, and because it's listed in the report it means our crawlers are finding it linked to (probably by a malignant link on your site - or sometimes a bit of javascript)
In this case it does have a proper canoncial tag on it, so all is good. Was the canonical tag added recently? I am surprised that our crawlers would report it as a separate page. But if it was added recently it might make sense.
3. This one's a bit more of a myster. If you look at this page: http://villasdiani.com/category/kenya-news/ The first image in the upper left hand corner has the alt text "Kenya Villa Rentals on the Top in Africa"
The only problem is the report says the link is on the homepage, and not this internal page.
If this was changed in the past month it may explain it, because we are reading the link report (which is updated about once a month) and not the crawl report (which is updated weekly). If you think there is an error in either of these reports we could ask the help team for assistance. They're usually very good at digging into technical problems.
Regardless, your site is looking very healthy.