I am a novice bitcoin user (at best) and was hoping to get some advice and input from the community of users who are much smarter than I about bitcoin in general.

I have been using bitcoin for a variety of transactions for over a year, but I really don't have the tech-mind to understand how it actually works from a network perspective.  I use only mobile wallets and exchanges and typically haven’t held bitcoin for too long.  

I want to hold some for the longterm – basically set it aside as part of my investment portfolio and not touch it for any transactions.

I have read about a number of "cold storage" options but still can't wrap my head around which one I should adopt.  After much reading I must say I'm still confused.

I am leaning towards a paper wallet (using a wired printer with no hard drive and an air-gapped cpu to generate the wallet).  I would like produce more than one address and split up my BTCs.  I would then store them in various safety deposit boxes.  Any input about what is the most secure way to generate this wallet would be appreciated.

I have read about Trezor, however I'm wondering if there is any advantage to this route.  What is the hardware defaults and/or the company goes out of business and I can't replace the unit if it's lost or stolen?  Is the mnemonic phrase that is generated compatible with other wallets?

In terms of using a seed phrase from a wallet like electrum or mycelium, I would still be required to store this phrase somewhere.  I would likely go the same route and put them in safety deposit boxes.  What I'm confused about is whether this seed phrase is only compatible with the same wallet from which it was generated.  If mycelium is no longer available, is there a way to use that seed phrase to retrieve my funds/wallet/keys?


Much of this confusion on my ends stems from me not having an understanding of how actual pairs of private/public keys are generated, and then also how a seed phrase is linked to a set of these keys.  

Any input would be great.  Thanks!