King Bright

Ok hey all :) I just started to study 3d-design, but at the moment im learning all the ways to model in Maya 2012... and lighting and baking (especially uv-mapping) is about half a year for me to go from now... but i just want to ask u some quick questions.... would be cool when somebody could answer me some of them... I wanna start creating prefabs and furniture (maybe also clothes but later ^^ ) the modeling of them all is what i already know how to do... but my problem is just, when i add lights and surface-light-materials to bake shadows it takes crazy time to calculate and render the texture... ambient occlusion goes inbetween 1 minute on a 2048x2048 map from a whole building.... and it already looks nice (i only need to figure out some uv-mapping issues cause of the seems i get...) but as soon as i want to bake global illumination, light only or light & color it takes too much time... about half an hour for only an single wall segment to bake to an 512 x 512 map... so my questions are: how do u set up your lights? how many? and wich kind of light? and wich settings you use for the lights and the mental ray render settings like fg / gi / ao.... oh and when i try to rotate the sunlight, it just turns to black ^^ dont know why this happens... but its confusing :-( oh and which is the best way to bake textures? should i bake ambient occlusion and an light only map to merge them both in photoshop? cause thats what i often read... but theres still the problem with the light only baking, cause it take a lot of time but still has a very poor output... and how can i get the textures i added in maya to my baked maps? or do i have to use the bake light & color option? my pc specs are: amd fx 4100 ( 4 x 3,6 (turbo-mode 4 x 3,8)), 8 gb ram ddr3 (1866), ati hd6870, and i have win 7 64 bit oh and before i forget to say: i have the trial of maya cause i get my students full version on 3rd march... i've read something like the trial is only 32bit but will it reall change so much in render time with the full version?