读图，判断下列各题题．

B

    (Shenzhen, Wednesday, 31 May)—Shenzhen traffic police fined 4,251 private cars 300 yuan each because they used the bus lane (公交车道）during the three-day Dragon Boat Festival holiday. The bus lane on the Luosha Road and Huishen Coastal Expressway（惠深沿海高速）to Dapeng was put into use on Sunday, the first day of the holiday.
    The bus lane only allows buses between 9 a.m. and 9 p.m. during holidays and weekends.
    To make sure traffic on the bus lane moved smoothly, police officers were sent to work along the road
using cameras and drones（无人机）to get information and photos of the vehicles(车辆）that entered the bus lane against the traffic rules.
    Information from police shows the bus lane has reduced the time it takes buses to get to the east of the city. A tourist took a holiday bus to Dapeng at noon from the Luohu Stadium Stop, while his friend drove a private car. The bus arrived at 12:48 p.m. The private car arrived at 2:05 p.m.
    According to police, the bus lane can also be used as the rescue passage for accidents that happen in the tunnels.

如图1，半径为2 的⊙P与x轴相切，并在x轴上从左向右平移．直线y=kx﹣4分别交x轴、y 轴的负半轴于B、A两点．在⊙P平移过程中，圆心P刚好经过直线AB上的点Q（﹣8，a）．

（1）求k值．

（2）⊙P从Q点出发，以每秒1个单位速度向右平移，

①同时，直线AB绕A点逆时针匀速旋转，当⊙P第二次与y轴相切时，直线AB也第二次与⊙P相切，求直线AB每秒钟旋转的度数．

②如图2，第9秒钟时，⊙P与y轴相交，PH⊥y轴于H点，E为第一象限⊙P上一点，EF⊥OH交线段OH于F点，M为PE中点，当FH²﹣FM²有最大值时，求E点坐标．