Well, I think that "thank you" is probably good enough. If you want to be a bit more emphatic, you could say "thank you, that's very kind" or "that's very kind of you to say so". Without knowing what your relationship is like, it's difficult to judge.

As should be clear from the range of different answers, it really depends on your local accent. Personally (I'm from the North of England) I pronounce them with the 'ng' exactly the same, but even then on reflection I've realised that's probably not even consistent all of the time. I'm not even sure how dictionaries decide on the IPA, given that there's no central authority on pronunciation of British or American English. TLDR; Don't worry about it. :-)

It refers to a state (country, nation) which practices extensive monitoring of its citizens, through things like CCTV cameras, DNA databases, facial recognition etc. https://en.wikipedia.org/wiki/Mass_surveillance btw your question would be better formulated as the following: What does ''surveillance state'' mean in this sentence?

A "night owl" is someone who stays up late into the night. If you're asking for the opposite as in someone who sleeps late, I'm not so sure of a common expression for that. Maybe "bed-head" or "bed bug"...?

Yes, they all mean the same thing. As a native British-English speaker (2) sounds slightly more American to me, but apart from that they are equivalent.

My own examples using new phrases

(1) go out of one’s way

This tastes good though I wouldn’t go out of my way to have this.
Just because they are celebrities doesn’t necessarily mean they have to go out of their way to make every person laugh.

(2) It just happened that S+V

I wasn’t looking for this but it I just happened to be in a grocery store. So I thought I should buy it while I was at it there.
My friend just happened to be there waiting for a bus.

(3) get someone to V

Sometimes I sweet talk to my dad to get him to do chores.
When I was younger, my mom used to promise me that she would give me an allowance to get me to study hard.

(4) (what's the example?  Is it Could've/Wouldve)

When we were younger if we could’ve gone anywhere in time, it would’ve been to be an adult because as a kid, an adult always looks cool and there are lots of things that we can do only when we <strike>only</strike> become an adult.

(5) rip off

The man in a the store ripped off my brother when he got some snacks. So he eventually paid twice as expensive much as they should be have been. I asked him why is that they have got to be they were so expensive but he just made loads of absurd excuses.

(6) star-struck

Now that it’s the Olympics, I’m star-struck by athletes in the events that I’m looking forward to.

A baby is "conceived" when a sperm fertilises the egg. The implication is that this happens when a couple have sex in a bed, which in 10% of cases was bought at the Ikea furniture store. You might also say: "My brother was conceived in the back of our car". "Conceive" can also mean to derive an idea or concept in the mind. "Conceived as an online book seller, Amazon has reinvented itself time and again..."