Short answer, it can have both.
QR code is just a representation of a string. That string can just contain the address or the address and the amount of BTC.
It depends on the software of the smartphone how the string is constructed and/or red.

It is like winning the lottery.
And if there's a chance, it can always happen again.

Simply said, it's the price of the mining gear and the cost of electricity.
The speed of mining 1BTC depends on your hash rate compared to the total hash rate, and of course the difficulty.
For example:
current difficulty: 908,350,862
nowadays you can rent hashing power, should include appr. the price of device + electricity: 10 dollars/GH/year
hash rate: 1825GHz
1BTC/day

So that's 18,250 dollars / 365 = 50 dollars/BTC

edit: 10dollars/Ghash/year is a pre order product expected in February 2014, so with the difficulty changing fast calculations won't hold for long.

When using shell script, does the log file has write protection?
If for example, two notifications being issued, can the text become scrambled if the two scripts trying to write at the same time?

I think there not really a maximum time, it just stays in the transaction pools of the miners until maybe a timeout.

You make almost no money mining Bitcoin today. It takes a big investment to buy ASIC devices, and the question remains if you can ever break even.
Take a look at http://bitcoinwisdom.com/bitcoin/calculator and see for yourself.
Mining alt coins can be profitable, but the window of opportunity is small due to the fast increase of difficulty.
You're also have to be lucky, there are many alt coins these days and only a few become ever profitable.

- I'm not really into trading, but hey, if it becomes very easy maybe I give it a shot.
- Nice GUI of course.
- I would donate if I used it for a while and liked it.
- Not sure, I would need more information.

But sounds as a nice project, keep up the good work.

bitcoin.de is fairly good to use when you buy from Europe.

If you mine Bitcoin I strongly recommend using pool mining, just look for a different one.
Otherwise you won't mine any Bitcoins at all.

No, not again...
Well, I guess it's time to buy again.

Depends on how big your investment is. If it's substantial, I would say no.
You should store it on your own computer, but know what you are doing.
Everything you try, try it with a small amount and know for sure that it went OK.

In the Netherlands you can use it to order takeaway food. thuisbezorgd.nl

5th reply is maybe a good idea.
https://bitcointalk.org/index.php?topic=373086.msg3991772#msg3991772

Yes, you're right. The address is more for human use I think.
It is shorter than when it's written in hexadecimal and it's base58 to get rid of the 0O, I1, etc pairs.
Different addresses could look the same if it was base64.

Search forums thoroughly for scams. It will always be your own judgment if you have safe software or not.
Don't let Windows put you off, they warn you for almost everything.  

It's a good thing you want to invest your time in instructing the general public Bitcoin.
Are you planning only to tell how to use Bitcoin or also how it works?
For the general public to use something, they don't have to know (all) the internals.
And it's also quite hard on how to construct a good explanation.
I have seen many and often they want to tell too much.

I'm interested in the English version, maybe I will link it as an introduction to Bitcoin on my site.
Keep us updated.

Agreed, I hope though that the intrinsic value goes up fast if it's used more as a payment system.
The transaction fee is taken care off in the next release 0.90. Hope they finish it soon.

No, that would be very very hard.
Only if it is changed in the protocol and the majority of the miners agree with it.