Congratulations on getting out there and starting to run again. I had that urge a week and a half ago after running on a real track with spikes for the first time in over 10 years.
I think that with good training you can meet your goal for the 100m, I don’t think your goal for the 400m is reasonable. Going from 75 to 60 in about 6 weeks is too much of an improvement to be reasonable. You need to take off 7% of your 100m time to meet your goal; you need to take off 20% of your 400m time to meet your goal. For the average person (since I know nothing about your athleticism and fitness level relative to your ability), running a 1-minute lap is very difficult and is not an easy accomplishment. If you plan to run sub 60seconds, a better goal would to do it next year. Good luck!