I don't think adjectives can stand alone, in that way, so that the adverb "vizuri" would always be the logical interpretation of this sentence, not "I see good things from the ki-vi class".
Someone else should chime in, because I'm not really sure, but I think an exception to this could be "Ninaona wazuri" ("I see good people"), because wazuri could be short for "watu wazuri", and wazuri is not an adverb, so that would not be an option.
No it can't, if you want to say "I see good things" or "I see beautiful things" you would have to say "ninaona vitu vizuri". Ninaona wazuri doesn't mean "I see good people", it means "I see them as good" (could also include animals). Wazuri isn't short for watu wazuri as far as I know. If you want to say "I see good people" you would say "ninaona watu wazuri".
There are some cases in which case the adjectives are used without subjects (elusively), but as the3lusive said, generally you would add the object. But especially in proverbs/sayings one might find adjectives by themselves: "Kuishi kwingi (ni) kuona mengi." - To live a lot (/in many places), is to see many (things).