2. There isn't a max height on the logo, but aesthetically you would want it similar to the default size so it fits the header appropriately. There is a provided PSD to assist you in create the logo.
3. Most frameworks do not support this features because of how it handles module outputs. You can view all the positions here:http://www.shape5.com/demo/oasis/index.php/features-mainmenu-47/template-features/92-module-positions