1. It's good RolePlay idea, accidents like dodge at bed with sleeping dwarf are very rare. If dwarf on duty will be very tired, he will go there to sleep. When he is off duty, he will use his bedroom to sleep or barack bed OR dormitory bed (in this order).
2. You can assign individual equipment (like choosen by you sword or pick, or artifical armor), when Indiv Eq will be checked, he will leave it in barack marked as Indiv Eq armory. Squad Eq are all uniform pieces, who are assigned just by squad asigment (not selected by you, but just some general Lether armor).
3. Because some odds, They are leaving mess when there are not enough chests/bags. Dwarves seems to use randomly chests and cabinets and They do not use armor stands and weapon racks at all*. Put one 2 chests for every dorf.
* I once saw individual asigned, named axe in weapon rack.
4. It depends. Usualy it's good idea to have separated sleeping and training baracks, because people are often puting They barracks near front gates. Sleeping dwarves do not wake up, when something will attack them, because They beds are soo unconfortable.
Noise spread 8 layers in cube when you are digging, wood cuting or removing constructions. 4 layers for engraving, smothing and carving fortifications. Cave in propobly cause 16 tiles around (need confirmation). Its strange, but bashing your doors is not producing any noise! Fight too. Workshops are not producing any noise now (but in previous version, They was). Not every noise is waking up your dwarves, but when They are waking up, there is notification about bad sleeping.