Is the "Dyw" preceding "Owen" necessary in everyday speech? As opposed to just "Owen ddim eisiau siocled".
Yes. Leaving it out would be the equivalent of saying "Owen not want chocolate".
Is the 'dyw' bit the equivalent of 'dw' in 'dw i'n' but just for the third person pronoun?
Kind of - better to say that dyw is to yw as dydw is to dw, as dyw and dydw are both negative forms.
That said, dydw i ddim can turn into just dw i ddim, so in that sense, dyw is equivalent, yes. But unlike dw, it can't be used for positive statements.
I don't understand, in previous lessons it was stated that you SIMPLY add "ddim" and nothing more, here you introduce new "bod" forms, so I thought that you use negative or question form of this verb only if you question or negate "bod", e.g "I am not a boy" - "Dydw i ddim bachgen", but not if you question or negate a verb-form as "hoffi", "eisiau" etc because we learned "Dych chi ddim yn hoffi coffi" and not "Dydych chi ddim yn hoffi coffi". Wait, in negative form you can use both. So, you kinda confused us stating that you JUST add "ddim" to a sentence since there weren't given any forms except of "Dw i" and "Dych chi" which can remain the same in both question and negative form?
In more formal Welsh there is a positive and a negative form of the verb "bod". So "Rydw i" but "Dydw i ddim".
"Rwyt ti", "Dwyt ti ddim".
"Mae o or e/hi", "Dydy/dyw o or e/hi ddim"
"Rydan/Rydyn ni", "Dydan/Dydyn ni ddim"
"Rydach/Rydych chi", "Dydach/Dydych chi ddim"
"Maen nhw", "Dydyn nhw ddim".
But as I said this is formal Welsh and we teach a more colloquial form so for most of these we drop the "Ry" and the "Dy" so we end up with "Dw i" being both negative and positive for "I am" with the "ddim" being the only marker of the negative. Now this doesn't work with the third person forms so you have to use "mae" and "dyw/dydy" and "maen" and "dyn". Also to note in "I am not a boy" you forgot the "yn" I.e "Dydw/Dw i ddim yn fachgen".
Yes, thank you, it fits in your previous answer to me. Thanks for correction also. But does "yn" require mutation if used as "in"? So that you can discern "I am a boy" from "I am IN a boy"
"Yn" isn't used in that instance as "A boy" is indefinite. Instead "Mewn" is used i.e "Dw i mewn bachgen". So if you said "I am in a school" it's "Dw i mewn ysgol" but "I am in the school" is "Dw i yn yr ysgol". Other than that though "yn" "in" cause a nasal mutation i.e "Ym Mangor" (In Bangor, also note that "yn" has become "ym" before "m" and it also becomes "yng" before "ng"). "Yn" as a verbal particle causes soft mutation on the other hand, although this only affects nouns and adjectives not verb-nouns.