Are single entry tourist eVisas easily granted to European citizens, and how many can one get in a year?

I've never heard of someone being denied a tourist visa when they qualified for it.

But how many tourist visas you can get in a year is irrelevant. Just because you have a visa sold by an embassy, doesn't mean that immigration will let you into Thailand. They are the ones who make final judgment on your entry, whether you have a visa or not. And people who try to spend too much time in Thailand as a tourist (thereby demonstrating they are not actually tourists) tend to have problems.

You can get a multiple entry tourist visa, which is valid for 6 months and allows 60 days on each entry. Some people can push this to almost 9 months. But others have reported being interrogated at the airport on their 2nd entry after spending 90 days in Thailand already.

One thing is for sure, if you do manage to get 9 months out of it, you'd best not return to Thailand as a tourist for about a year.