Translation:Even a small flower needs a lot of water.
Even as a native speaker I'm not entirely sure if there is a major difference, but if I had to guess I would say "även" means "even" more in the neutral "also" sense, while "till och med" means "even" in the "even those, believe it or not" sense. There's more emphasis. I find it difficult to explain in clear terms.
Yeah it isn't anything we can control, and it isn't specific to our course, it's a general Duo thing. So it's a question for the general forums, where it has indeed been discussed quite a bit lately. Here's a link to one post about how the desktop version has also been dumbed down: https://www.duolingo.com/comment/14171868
I suggest searching the general forums and participating in the discussions there.
The desktop version is still much better than the mobile, so if you have any chance at all I'd recommend working as much with that as possible rather than mobile. But while Duo has promised to address the issue, in practice they've only been making it easier so far, especially on mobile, but on desktop too.
ps thanks for calling us 'awesomesauce' :D
Those are the definite singular forms. :)
lilla is the base form: den lilla katten, det lilla huset. Note that it has the same form for en-words and ett-words.
lille is an optional form for males: den lille pojken. It's a rest from when Swedish used to have masculine and feminine in the language.