there are a few diffrent answers depending on how you start your question in welsh...
question beginning with 'Ydw..?' , the answer will be 'wyt' : Do I have to send her a thank you letter - (in welsh : Ydw i gorfod danfod cerdyn diolch?)
question beginning with 'Oes..?' , the answer will be also be 'oes' : Do I have to send her a thank you letter - (In welsh : Oes rhaid i fi ddanfon cerdyn diolch?)
You can say "I am Welsh" by simply stating "I am Welsh" in English. In Welsh, you would say "Cymraeg ydw i" (I am Welsh).
'Our Friends' in Welsh is 'Ffrindiau Ni' :)
To say "your house" in Welsh, you would say "eich tลท".
Cymraeg
"Na" is the word for "no" in Welsh.
"y diwedd" is how you say it in Welsh language.
In Welsh, you would say "Rwy'n cytuno" to say "I agree."
Welsh dragon in Welsh is "draig Goch".
You can say "it's nice" in Welsh as "mae'n braf."
Yes in Welsh is "ie" and no is "na."
Daeargi Cymreig
"She is" would be "mae hi" in Welsh.