mount a switch in a rack

1. Should everything face one direction, e.g. servers, switches, routers, or should I / can I have servers face one direction and then for switches, etc that don't occupy the whole depth of a U, share the same U on both sides? For some reason, we are using both sides of the rack right now. 2. Is it best practice to have everything that comes into the server room go into a patch panel, and then have short patch cables from patch panel to switches? 3. Should rack servers be wired to patch panels, and then to switches, or is that a waste? Should I just wire the servers to the switches using patch cable directly? 4. Should I use M6 cage nuts and screws for everything, if possible? I have a Dell rack, which has the square (or rectangular) holes.  I have a mix of equipment: Dell, Netgear, HP, yada yada. 5. I have some 1U battery backups.  They are quite heavy.  Is it realistic for me to actually mount those? They only came with the mounting bracket on the front.  Common sense tells me not to mount it, but I've heard people say that they are definitely mountable.  Your thoughts? 6. For small devices, e.g. cable modem and Cisco router that came from ISP (backup broadband), what's the best way to keep that organized in a rack? Should I use a shelf? Are there any better options? 7. Should I leave space between devices in the Rack, for cooling, or is it ok to place devices contiguously? I wasn't sure if that would cause servers to overheat. 8. Any recommendations on temperature /