It was the the British India Army. Try to get it's name correct please. One prefix can change a meaning entirely. You know what a Indian is. You know what a West Indian is. You know what a American Indian is. You know what a Dutch Indian is. One prefix changes the meaning entirely. I reiterate it was the British Indian Army which was diveded into Pak amnd Indian Armies in 1947.
No they are not. The only reason why Pakistan ended up with such a large army was the British had discriminated by choosing only certain areas in all of South Asia to recruit their manpower. Three districts were heavily favoured, Attock, Rawalpindi and Jhelum. In 194 these made Pakistan this all regiments recruited from there went with Pakistan. That is why Rawalpindi was PA HQ right from start.
It was this 'gift' of colonial history that gave Pakistan the resilience and backbone - otherwise no amount of peddling Islam or singing songs in name of Shaheed-e-Millat Liaquat Ali Khan would have saved Pakistan from Nehru's attention.