Can precum soak through pants and cause a could it be transferred from an object such as a phone and still be viable?

Not likely: The scenarios you described are not likely to result in a pregnancy. If you and your partner do not wish to be pregnant use contraception every time, all the time. She may wish to get an IUD or hormonal implant. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.