Just remember to wear oven mitts when you're baking textures
You can also use tools like Gimp to produce normal maps. Normal maps are not created from just multi-resolution models, but also from random images to add deformities such as cracks, scratches, bumps. In some cases like with relief mapping (parallax bump mapping), brick textures can appear extruded while observing at certain angles. None of these situation calls for an original high poly model. My TexGen tool can procedurally generate normal maps if that interests you. There use to be another good tool called MaPZone (by Allegorithmic), but it doesn't look active anymore. At least not the free edition. He's gone pro now. There's also Genetica, which has been around a bit longer. Blender can do these as well if you work with its node editor. If you learn python, you could even write your own algorithms.
For lightmaps, stick with a pro modeling toolkit. Ideally, use a real level editor created by game devs (such as Havok) since they simplify the matter for you. Blender can do this as well, but it's a lot of manual labour. When Blender renders an image, by default it renders the scene to a new image. You can tell the renderer to only render lights and shadows (or ambient occlusion) and specifically to a texture (one that is already assigned to an object). However you need to save that file afterwards and do this for every model. Best to write a python script and go watch a movie while it bakes.