The ranks of lashkars have grown to 8,000, according to local leaders, since the Army retook the valley in June. Some residents worry about militarizing the population.
The attack, which killed at least 90 people near two Taliban-hijacked trucks, is a setback for NATO's push to limit civilian deaths.
The arrests show that militants still pose a threat throughout the country despite the death of Taliban leader Baitullah Mehsud.
A council picked Hakimullah Mehsud to head the alliance, two days after another senior figure said he had taken over. The announcements may signal infighting, which in recent weeks has led to bloody clashes.
Voting today will test the legitimacy of the government and the credibility of the international counterinsurgency strategy.
Pashtun residents say militants have imposed extremist views on the population, displacing centuries-old traditions.
The 60-page code of conduct, issued in the runup to Aug. 20 elections, urges fewer suicide bombings. US and Afghan officials say it's propaganda.