Sending BTC using Seed Hex or mnemonic

I’m interested in sending BTC from wallet to another and probably automate it through some libraries.

I have a question: if I have a seed hex or 12 words I can generate all my wallets (addresses, private keys) with BIP39 mnemonic tool.

How could I know what of external wallets (private keys) I should use to send btc using libraries assuming it usually changes?

How could I basically send BTC to some wallet having only seed hex or 12 words?

Why does Bitcoin no longer have checkpoints?

I’ve read that checkpoints in Bitcoin were removed because they were not preventing any meaningful attack.

Why should a regular checkpoint not prevent majority attacks? For instance, if a checkpoint is made every N blocks and (for example) 3/4 of the hash power agrees, would this not be possible to be used as a mechanism to create a permanent confirmation of the transactions before the checkpoint? Assuming, of course, that clients would check for those checkpoints and enforce them to be included in the valid chain.

python-bitcoinlib | Create Private Keys, Public Keys and Addresses – How to Do It?

I’m trying to use the python-bitcoinlib library but its docs aren’t entirely clear to me.
I’m a programmer but quite new to Python, and not very versed in the Bitcoin protocol.

What’s the process, code-wise, with the library, for the following?

  1. Generating a private key
  2. Creating a public key
  3. Creating an address from the public key

I tried various things and am not completely sure what arguments I supply to what functions, and what functions I’m supposed to use in the process.

I’d appreciate a lot, and I think it’d help me the most if I were provided code for achieving each step.

I was able to follow the Bitcoin protocol (specifically, the developer reference and the developer guide on bitcoin.org to do all of those things, and I’m looking specifically how to do it with the library, so I could have my code fully compatible with other functionality of it, since I’d like to use the library for additional purposes.

recover wallet in electrum from hex mpk

I´m trying to recover a wallet from which the Master Private Key (mpk) in hex format and the number of used addresses is known.

Till now I could manage to convert the hex mpk to the wif format and import this to electrum. But here to history seems to be totally lost.

Is there any way to recover the full wallet and history (not neccessary with electrum)?

How to fetch incoming transaction in Ripple

Currently I have setup ripple mainnet server and provide availability of XRP trading, If any user submits the transaction in his account from the external wallet, How I know which transaction performed? Currently, I have used WebSocket socket and subscribe all account to the listener, So when any transaction comes in subscribed account then it will catch the transaction. But the issue is that when my xrp server is down or listeners missed any transaction then how we fetch incoming transaction later.

How are newly created bitcoins are validated?

I’m trying to understand how Bitcoin works but there’s a concept I can’t get my head around.

I understand that transactions are validated by checking the signatures of each input is valid. However how do you validate new bitcoins or rewards that have entered the system through mining if these don’t contain any any inputs?

For example if you’re checking a transactions inputs are valid eventually you’ll reach the point when the inputs were originally mined, so how would you know these were created legitimately?

How do my bitcoin peers become diversified from the set of stable nodes?

I read through a variety of threads on initial peer discovery like How do Bitcoin clients find each other? and How does the bitcoin client make the initial connection to the bitcoin network? and they all say that if it is your first time connecting then you connect to the DNS seeds which give you a list of hard-coded stable nodes. If it is not my first time connecting, then I connect to whoever I was connected to before.

It is not clear to me why every client would not everyone always connect to these same set stable nodes every time (after the first connection, they are now in my dat file and I always use them)? By what process do my peers become diversified from the hard-coded stable nodes?