Homsa... is he watching cbeebies or was it NickJr by any chance? there's a programme where one of the doll characters speaks French dd is quick on picking such phrases up as well. Like with watching Dora the Explorer I get 'largo' and 'corto' (apologies for the spelling that's what it soudns like anyhow)
For the babbling... my friends son, purely German speaking, for the first 3 years I couldn't understand a word he was saying! 'Gauku' was his word for 'Auto'. My dd for ages called spiders 'saba' no idea where she got that from. Even asked my childminer whether that's anywhere close to Pakinstani dialect spoken in the house but that was a negatory.
For your ds possibly babbling in English... that depends on what his major influence is. As I said dd was exposed to mainly English from 5 months on so English is definitely her first language. However I met a Spanish lady in Kew Gardens a while back and her dd had been with her the first 3 years so first language at that point was Spanish.
As for speech impediments and multilingual. IMHO if a babe has speech problems it's usually not down to which language he speaks but to other factors, like hearing etc. (not that I really know anything about this but I'm guessing)
He might just be plain lazy like the budding astronaut in this thread.
My brother (he's a psychologist) told me a joke when I worried about dd being slow with her speech... here we go... need to translate and shorten it a bit...
Little Hans's mother was terribly worried because despite of all her coaxing, prompting, efforts etc. Hans hadn't uttered a word in all his life and with his 6th birthday approaching she was giving up hope. until suddenly one day Hans said in perfect tones 'Mum, the soup is cold'. She nearly fainted and then jumped up and down in joy. Once she calmed down she asked Hans why he never said anything before. And what did Hans reply?.... 'well everything was fine so far'