Is it possible to get a menu, where you can select between texture packs, so you can have Vanilla Textures and for example BDCraft?

It's not on the roadmap, as each texture pack needs a new renderjob to be done, which take a long time

that is currently not possible, however, you can define different texturepacks and have multiple maps next to eachother for each texturepack.

Ok... Will something like this come soon?