The last time I was in Prague was close to this time last year, about the first week of April. The weather was great!

I don't think you'll have a problem finding a computer, either at your hotel or one of the internet cafes. The hotel I always stay at in Prague is called the Hotel Pav (it's owned by Best Western now), and they do have some computers for guest use on their main floor. And an AWESOME breakfast included in the rate! The quarter it is located in is one of my faves in Prague too. But yeah, you're not going to find an abundance of bike lanes or even other cyclists in Prague like in Denmark or Germany.

Frankfurt is not my favorite German city...I find it kinda boring and too business-like, but I've heard great things about Freiburg though I've never been. Southern Germany is great in general. If you get to Munich I think you'll find it to be quite bike friendly.