Prayer

I would like to gain more insight and understanding into what a pidyon nefesh is and if it is indeed a holy way of truly redeeming ones soul. What has been the experience when requesting such a prayer?

If you miss davening Shacharit and you have to make it up at Mincha, do you just recite Amidah twice, or do you also include other prayers that are normally part of Shacharit. And if you do, where and in what order do you include them?

If there is a bris at a later minyan in our shul does the earlier minyan say tachnun?

If you are saying perek shira and Nishmas as a segula for 40 consecutive days, do u have to say it before shikia? Also, can you say it on shobbos?