Nawaz left Pakistan for London on November 19, 2019 whereas the voting on the extension on the army chief took on Jan 8, 2020.
Answer to your first question: Why did Army bring Imran Khan by rigging election instead of their own Pervez Musharraf?
Answer to your 2nd question: When opposition came to know it was Army brought IK to power? In your views, Army given relief to Nawaz anticipating there will be vote in NA for the extension of COAS and PMLN will vote despite knowing Army brought IK to power. Did Army give this deal only to PMLN or other parties as well that in future if anyone sentenced to jail on corruption will be let go to London for treatment?
Last thing, please provide few suggestions to make free and fair elections.
Yes Nawaz went first and voting was later but that was part of the deal. Why PML-N voted army chief extension then?
Pervaiz Musharf cannot be bring as he has zero popularity in entire Pakistan. Army can make 60 to 100 but cannot make 0 to 100. It was clear in 2013 elections that Pervaiz Musharaf cannot win at all. They did not tried to PML-Q even as they knew that they have their base only in Gunjrat and little bit more in other areas.
There is continuous negotiations goes on as PML-N has a lot of pro- army people within it. Shahbaz Sharif and Khwaja Asif are pro-army in Nawaz camp for example. PML-N never ever disconnected with army completely but they were not their own party like in 1990. You can see hundreds of X-army or on job men in Khan government and Khan party is completely a King's party like it was PMLQ in 2002 and PML-N in 1990.
PML-N is Punjab party and every component of establishment including army has soft corner for PML-N. PML-N still got one crore 29 lakh votes in 2018, only 30 lakh votes less than Khan party despite a strong political engineering against them. Musharaf has also tried to dump this party but they came back strong. I think Musharaf performance was better than Khan government and even if they cannot stop PML-N then it will be hard to dump them for ever. They are strong public voice and let the people decide who they want.