Hi there,
Baden-Oos is no longer a public use airfield. It is a special use airfield for the local flying club and I don't think you will be allowed to land there.
EDSB is an ok airport. It has a long runway, ILS and light airline traffic. Don't be surprised: approach control is done by the French (Strassbourg approach).
It used to be an airbase and everything is quite spread-out. Last time I was there the GA Terminal was rather run down and remote but this may have changed. There is a regular bus service from the main terminal to the city (bus 205 I believe).
Landing fee and parking for one night should cost you around 30 Euros. I suggest you call them or check their fees online.
Hope this helps!