I have a lot of Sats and have used cold wallets but didn't like them so I put everything into a hot wallet (Coinomi) which is very easy to use with both my desktop and a mobile app and seed phrase recovery (which I like), but I do worry about long term security.

I want to keep my coins on my own node (the latest Core) which I have had running for a month now, but I'm worried about a few things:

1. Recovery is by a .dat file with no seed phrase unless I am missing something, and I suppose I would need to save the .dat file to another computer in case my node fails or the computer running the node crashes. Do I need to protect the .dat file in the same way I would protect a seed phrase? Can someone with the file gain access to my coins? If my box crashes will I have to download the whole Core again in order to recover my wallet with the .dat file? The Core tutorials I look at are either to technical or don't cover things simply enough for newbs to understand.

2. I read articles on how to connect different wallets that use seed phrases to my node but they require me to run an Electrum server which thing is waaay beyond my technical abilities as it has no GUI. Is there a "Connect your wallet to Core for Dummies" guide anywhere?

I love supporting the network by running Core and if thats all I can do I'm fine with that but I would like to take it to the next level without having to go back to school to be a rocket scientist lol...