The first thing to do is establish where the leak is coming from. It can range from an oil pressure sensor, oil pan gasket, front crankshaft seal, rear main oil seal. The best way is to clean bottom of engine, add oil dye to crankcase and then check in a few days. You will see the dye at the point of origin.
Repair prices can run from $75 for an oil pressure sensor to several hundred dollars or more if it is a rear main oil seal. But there is no way to give an accurate estimate without knowing the source of the leak.
Well, before assuming the worst, do what I suggested so that you actually know what is leaking.
I think he may be referring to the rack & pinion unit, which is the steering gearbox. You will be looking at around $700 parts and labor for that.
Not really sure what he is referring to in the rear. May be able to help more if he can you a better description on that.
You can get oil dye from any major parts store for under $5. The crankcase is just a common term for where the crankshaft resides, part of which is the oilpan. Just pour it into where you add oil.
This what the rack and pinion looks like. You can buy one from any of the major parts stores, they run right at $250 at autozone:
As far as driving long distances, there simply is no way for someone who hasnt physically inspected the vehicle to know how safe or reliable it is to drive for long distances.
A severe oil leak can of course cause engine damage if oil level isnt constantly checked.
If steering is loose due to worn rack and pinion, then it can be dangerous to drive. If it is leaking power steering fluid, you might be ok, unless you dont keep the p/s fluid topped off.
As I said, without physically inspecting the vehicle, I cannot accurately tell you if it is safe to drive a long distance or not. No one can without physically inspecting it