Ladies 40+, tell me your laundry secrets!

I’m struggling with a few things and could really use some "pro tips" from the experts:

1. The "Seatbelt Wrinkles": My t-shirts and polos are already wrinkled before I even arrive at work (usually caused by the car/seatbelt). Is this just the fabric and therefore unavoidable, or is it because my clothes are too stiff—or perhaps not stiff enough?

2. The Smell: My laundry doesn't always smell fresh. I use long wash cycles, but I air-dry everything indoors on a drying rack (no dryer). Today I hung some towels outside on a line for the first time, and they smell so much better. Is my laundry smelling "off" because it's taking too long to dry indoors?

3. The Machine: The washing machine is brand new, so that shouldn't be the issue.

4. Softener vs. Alternatives: Is it true that fabric softener is bad for your machine/clothes? Should I switch to white vinegar or citric acid? If I use citric acid powder: how many grams should I dissolve in a liter of water, and how many milliliters of that solution should I add per load?

All other pro-tips are more than welcome! Thanks!