Minor nicks and scratches have a lot more impact on value than performance. But even minor haze really does cause problems. You might shoot quite a lot of pictures without it showing up at all, but get some contrasty light or a person against a bright wall, and then it shows up and makes a mess of things. Luckily that one is usually not a big deal to fix.
On the issue of oily mess with lens cleaners; ROR will certainly loosen up any oily residue. I use it when I need the extra help, but expect to have to do 3 to 5 applications to get the mess cleared up. That is on a lens that hasn't been cleaned with it before (even a new lens, in my experience). I don't know where the muck comes from, but it doesn't seem to come back to any great degree once thoroughly cleaned. I mostly use breath with microfiber cloths, and a lens pen. ROR if necessary.
The Seneca lens - don't take my word for being a RR, that is just an educated guess. I'd just hate for you to be disappointed if you are expecting something else. I've always meant to try RR's since they seem like neat lenses. I couldn't make out the short focal length, maybe 6 or 8". You should be able to focus either.