Hi Metallo,

Looks like a bad leak there. To simply answer your question, yes you could replace the condenser with a new part. Add about 20ml of fresh refrigerant oil into the new condenser's port before installing. Go to AC shop, let them vacuum out the system and recharge with R134a. Done.

However things with AC is not as simple as that. There may be possible issues as you mentioned plus many more. Possible issues are:
1. Did all oil leaked out or just a little bit?
2. Did the AC compressor suffered some wear as oil leaked out?
3. Do you need to flush all wear particles out or just do replace and recharge?
4. If there was compressor wear could you continue using the current compressor or replace new?
5. Is the orifice tube (assuming this car uses CCOT system as most 940) need to be replaced as well?
6. Is there any other leak in the system?
7. Is there going to be another leak as the system is already 23 years old?

With complex issues like these its best to let AC shop handle the whole thing. And then expect some new issue to appear in the future as age takes its toll on the system. You could let the shop flush the system, replace any old O rings, install new compressor, do evaporator cleaning, refill fresh oil, vacuum and recharge. This takes much more $$ but its better for the long run.

Regards,
Amarin.