What is gettxoutsetinfo used for?

Could you please explain gettxoutsetinfo, what is it used for? What are the different fields in the output?

I assume that it’s used to calculate the amount of the unspent trasaction outputs in the blockchain. What is bytes_serialized and hash_serialized?

  "height" : 225494,
  "bestblock" : "00000000eb0443fd7dc4a1ed5c686a8e995057805f9a161d9a5a77a95e72b7b6",
  "transactions" : 335344,
  "txouts" : 2221582,
  "bytes_serialized" : 72130407,
  "hash_serialized" : "3d14832b1b468f52ce942d4b9dc0c76a54fa6865207ff64540105403e3109f43",
  "total_amount" : 10886823.50380013

What’s “walletconflicts” in listtransactions method output

Here’s an output of listtransactions method

"account" : "",
"address" : "mz2A28GQxWrYgMn2z9pRqaUFNqTMyhk1sJ",
"category" : "receive",
"amount" : 6.30000000,
"confirmations" : 157,
"blockhash" : "00000000befa3ef184f6c3cdec8814b945bad9e3f7ce9eb38e3102bcf4c030c0",
"blockindex" : 9,
"blocktime" : 1397675516,
"txid" : "f517350f088d235878ecab8d5241f0b6e59a4081eec22031c449d0d01d79ed66",
"walletconflicts" : [
"time" : 1397672026,
"timereceived" : 1397672026

what’s walletconflicts, it’s array of what ? transaction ids, maybe ? i couldn’t find any documentation even in Bitcoin console.

Do physical bitcoins or altcoins actually carry value?

This question establishes that there are physical bitcoins that can be bought and I recently just bought a physical Dogecoin as a trinket but I can’t help but wonder if there’s a solid value related to these coins.

Bitcoins can be found for 1, 10, and 25 BTC and I just bought my Dogecoin coin for 10 USD (18947 Doge after shipping and handling). If someone were to hold onto these coins for years and attempt to sell later on, what would they be worth? Is a 1 BTC coin always worth 1 BTC or, like a collectible, is it only guaranteed to be worth what somebody will pay for it?

I know it’s not officially backed or anything, but is it reasonable to think that if I bought it for 1 BTC that somebody else would pay me 1 BTC for it later even if the value of BTC changes?

Can I spend/transfer bitcoins directly from cold storage?

From reading previous articles I understand that you can receive bitcoins to an address even if your wallet is in cold storage because the bitcoins sent to this address is recorded by someone on the block chain. Is this correct? and who is this someone?

Now If I have bitcoins stored in an offline laptop (I believe this is called cold storage) is it possible I can create some sort of QR code with my offline laptop and just have my mobile Android bitcoin wallet snap the QR code and wallah the bitcoins are transferred from cold storage to hot? Do I also need to enter my private key to enable this?

Can I download blockchain updates from somewhere?

I use Bitcoin only on rare occasions – say once every month. I want to avoid long waiting times for downloading and verifying blocks that consequently await me when I reopen bitcoin-qt. There are many options available for downloading the whole block chain when one starts out (like the blockchain torrent or the blockchain on Sourceforge). However, these options are full of warnings that tell you they should NOT be used when updating the block chain on an existing wallet but rather only when installing from scratch.

Are there similar ways of more quickly updating the blockchain by downloading recent blocks from some other source?

Note: I am not looking for other clients, but specifically for alternative blockchain download options for bitcoin-qt.

How do I use walletnotify?

I have bitcoin daemon and I want to use the walletnotify option with a json-rpc call. Some of the examples use a “transaction.sh” file for walletnotify. What is it for?

What do I have to write in that sh file, to make walletnotify work for more than 6 confirmations.