~ is that possible or am I just paranoid?
it is not exactly a "man in the middle" attacks but it is possible. and that is why you must verify the signature of what you download, just like you did here.
~What I want to know now is that how am I able to restore my wallet from any given computer if my seed words have been created offline and therefore have never been able to be sent to electrum servers?
So how do I exactly verify that I own the coins without connecting my offline wallet to the internet?
with bitcoin you create "key pairs" these consist of the private part that you should never share, called "private key" and a "public key" and a hash of that pubkey called "bitcoin address". this process is a one way thing meaning you can get the pubkey from privkey and address from pubkey but the reverse is impossible.
in bitcoin you don't receive bitcoin the same way you receive fiat. there is a big database called blockchain which contains transactions. and what transactions do is that they transfer value to another key (your bitcoin address). and these transactions are included in the blocks by the miners.
now to "verify that you own coins" you need to look at that database. you do it with a wallet. the wallets searches that database for your address and gives you what can be called "balance".
this link is good to read:
https://bitcoin.org/en/how-it-worksFurthermore I wanted to ask if my wallet is 99.99% safe from any virtual theft since my intentions are to hold btc for long term purposes?
as long as your wallet stays offline and never used it is 100% safe.
when you use it like connecting the USB to your PC, you just need to make sure you don't connect it to the internet or infect it in any ways and you will stay safe.
Also in order to satisfy my mind that I will always be the owner of my btc I need to know what will happen if Electrum somehow vanishes and all the servers are shutdown how will I be able to restore my wallet from the seeds because no other program except Electrum would accept those seed words and only if they have been transmitted to the internet before, right ?
So basically I need to understand the concept about the way I actually stored my bitcoins and if it is safe enough for 5-10 years from virtual theft or any problems that might occur if electrum servers are shut down?
those keys that i talked about (the private key) is universal and can be used in any application.
the seed is a special way to create those keys all from a "master key". the code for electrum is open source and available to all. in case some day Electrum stopped being developed (like Multibit which happened recently for example) you can always find safe tools online that will accept that seed (like what electrum does for Multibit users) and if not (in worst case scenario) you can always ask a programmer to make you a simple script to retrieve your keys from the seed.
here is the link to the code:
https://github.com/spesmilo/electrumalso remember that these electrum servers that you connect to via your wallet are just bitcoin nodes that you are explicitly using to "check out that database for your balance"
