We were there last summer! Didn't see the interior of the places you mention because we had our own tent, but we saw the treehouse things on the waters edge (or maybe they were the tents). You could email and ask, they will be helpful I'm sure.
It's great, although it rained everyday (but not all day!) for the 2 weeks we were there, unlucky!! We have 3 DC (who were 7,4,1) - our pitch was the opposite end of the play equipment part on the lake - about 5-10 mins stroll, nice at that end as you are a little further away from everything but still quite close.
The play equipment on the lake is fabulous for the children - some in/over the water, other stuff on land beside it. Suits all ages - bloody fantastic. Its all included too in the price, I thought it was great. It is a fairly large place but so safe and nice, lots of places to walk/bike. There was a little shop which sold essentials, but supermarkets nearby for food shopping, etc.
In the summer they have children's activities (either free or only a few euros) and our two older kids loved it. The rota is on the wall at the cafe beside the lakeside play area. Football/games/rock climbing/crafts, etc. With the football/games type of activity - DS only speaks English but they made sure he was included and the other children helped out - we just had to tell the organiser he only spoke English, so when they were organising and getting teams together, they knew to make hand gestures, etc if they didn't know the words in English.
We really enjoyed it and would go back again if we were in the area. Was very impressed, especially with what you get for the price!! (sorry, that was a bit of a marathon post!)