msp430g2553 Timers questions

Hello,

I have occured some problems with setting timers in my project. 

1. 

code:

BCSCTL1 |= DIVA_3;

TACTL = TASSEL_1 + MC_1 + ID_3;

question:

What frequency that setting will give me? And how accurate it is?

2. 

code:

#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer0_A0 (void)
{
P1IE |= ~BIT5;
P2OUT ^= LED0;
}

My idea is to enalbe interrupt on P1.5 for the time set on timer, i.e. 10 sec (I'm counting pulses on P1.5). How can I stop timer's counting after single cycle?

Thanks in advance,

Bartek