I have a tablet I basically just use for Kancolle, however it's ~3yrs old now and is starting to slow down a bit and struggles to even play KC full speed sometimes - plus the screen is no exactly always responsive now lol, making combined fleets very hard. (It was cheap at the time tbh lol but I'm very much considering buying the new version because its still cheap and has better specs now, and if I get another three years from it that'l do me lol)
However, how easy is it to transfer your data/the game across? Can I just do the hoop jumping DMM thing, download the game again and sign in to get my data? Or would i have to stick a memory card in and see if I can put it on there.
Yes, you only need to download the game and log in with the same account to get your data back. It's the same reason why you don't get your naval base reset if you log in on a different computer or even a different browser in the same computer.
It will have to re-download some game assets that would've been cached in your old device (like ship images, in-game screens, furniture, BGMs, etc...) but this is general data that isn't related with your personal data (which is saved with your DMM account).