Question One: the guys have given a very good explanation!! Also some aircraft configuration (like on the 737 for example) would make it difficult to have fwd facing crew seats.
Most A320 family aircarft even have a swivelling seat between the rear doors just to keep an eye on the passengers
Bigger aeroplanes like the 777 have both (usually one fwd facing and one rear facing at every main door).
Question Two: some airlines decided to designate "ABP" seats on board. For example in Ryanair it is the first row near the galley(not sure about back row, but usually headrests are of a different colour too to help identify them) FCA generally is 1C-D and 2C-D and same at the rear, plus emergency exit rows. In BA we have no such thing. These seats are "reserved" to able bodied passengers for take off and landing who in an emergency could reach the doors quicker than anybody else. What happens though, especially when it's a free seating airline, cabin crew sometimes block these seats for themselves. They shouldn't really do it but we all need a bit of breathing space!! It's a day-to-day survival situation. Nobody likes to have passengers in their face when working in the galley!!
Question Three: Actually, as for UK CAA regulations, only door/emergency exit row blinds MUST be up for take off/landing. Some companies though have agreed to unify the rule for ALL the rows. I actually think it makes more sense as if for example one engine is on fire during landing I wouldn't be able to see it from my seat but pax in row 5 easily could!!
Same thing as hand baggage under the seat in front of overwing exits. CAA says yes it can be there as long as it's stowed correctly. Most companies (I can think of many) decided that all bags in that area should be put in the o/h lockers. I actually prefefer when there's absolutely nothing in the area. But with the amount of carry-on baggage allowed sometimes it becomes difficult to find another location!!
Have a good day!!
FBW
