If you haven't moved forward with any repair attempts yet, you might consider this.
1st, you're mechanic may or may not know what's leaking. It's an older car and I'll assume you engine and bay aren't exactly clean enough to eat off. I would;
1. Get a leak detection kit with uv light & dye, Follow the instructions.
2. Get an engine degreaser product of you're choice and follow the instructions to clean the engine. If you can, do it at home on jacks so you can underneath.
Soon you'll know exactly where the leak(s) are coming from. There are multiple oil additive products that can do a good job sealing up minor **** which you could try before going to any extremes. As for the power steering, I'd do the same except I wouldn't add dye, just clean it and add a "stop leak" product of you're choice.
A front differential case leak is what started my complete diy wire tuck and engine bay overhaul. Upon taking the FX to a shop for the state's annual inspection, the tech claimed the housing was cracked and that was where the leak was coming from. He couldn't have been more wrong. I repaired the front passenger side drive shaft seal myself for $10 whole dollars. Fixed.