A single private key can lead to different addresses, depending on the script it is used in - These include p2pkh, p2wpkh, p2sh-p2wpkh.
Electrum prepends the script type to the private key during export and import so that it knows which address to derive and check for outputs on.
There is a difference between a traditional paperwallet and a BIP32/39 based mnemonic and seed system.
Traditionally, a paper wallet would be for a single address, with a single private key. When importing this into another wallet, a possible concern was that the change from any transaction would not be returned to that single address, but instead be sent ...
Well "wallet" as storage of keys should always be under your control. There are online wallets for higher convenience, but as the old saying goes "not your keys, not your bitcoin". It's probably a bad term, but I'd rather say "local (SPV) node" instead of "wallet".
When you are sending there is no problem with malicious peers as the transaction is (usually) ...
You can specify the wallet options multiple times.
in your bitcoin.conf will load wallet01, wallet02, wallet03.
Running a pruning node simply means enabling the prune setting.
In Bitcoin Core, that can be done either in the bitcoin.conf file by adding a line "prune=N" (where N is a number in megabytes), or through the Qt GUI in the settings screen.
Electrum is not a full node, and never downloads or verifies blocks at all, so there is nothing to prune.
There is no ...
1) Which secure full node wallet implementations exist? Currently I just know of bitcoin core. Is there not any other one with a GUI?
I don't know of any others, apart from forks of Bitcoin Core like Knots. See https://bitcoin.org for an overview of various types of wallet software.
2) Can you use a Ledger device with those full node wallets?
What other full node wallet apps are available to select from for bitcoin?
See https://bitcoin.org/en/choose-your-wallet for a reasonable list
Is it mandatory to have an own server when using a full node wallet
Not really. Some wallets have an API that allows other software to interact with the wallet but the wallets are generally usable directly for ...
1) How can you run a full node wallet with electrum? what do you need? Or please link me to an understandable guide for that
This probably should be a separate question.
2) Do you have to be online always or can you set it up, fund your wallet, and leave it offline for months, and just from time to time use it for transactions?
You can use it only ...
Bitcoin Core is not affiliated with the website you downloaded the node installer from - bitsblock.io, and the official Bitcoin Core client does not provide functionality you ask about. I noticed that when you click on download button on this website it takes you to some restore form. This seems very sketchy - I'd never provide online my private key nor any ...