You can use both, but 'det' is used as a dummy subject, notreally referencing to anything, while 'de' would be referencing the values.
"Those", yes, absolutely.
"These" would technically be the translation of "dette (if unknown plural)/disse (if known plural)", but since the values mentioned are specified as ours, and not being compared to any others, I think using "these" is acceptable.
That is our values does not seem correct to me. Then you should say "that is our value".
"Det" is used as a placeholder, because "verdiene våre" has yet to be mentioned in the conversation. Once "verdiene våre" is mentioned, "de" would be the correct pronoun to refer back to them. You could also use "de" if it was somehow apparent to the listener that we were talking about a plural something, even if that something was yet to be named.
It's similar to what happens here:
"Det (introducing a new noun) er en bil. Den (pointing back to said noun) er blå."
So if I understand you correctly you could also say: Det er biler våre De er nye.
Even though "biler" is plural...
I really do not get it. .. I am not a native English speaker. I am Dutch. What does this mean?