Thank you so very much!

Please add something for somebody who has no idea of how to start.
I worked with Windows for 20 years. My Lazarus 3.0 runs at a Win 7 VM, which bothers me more and more by becoming outdated.
This I want to leave behind.
I want to migrate to a Linux Mint Cinnamon 22 or so-VM and Lazarus 4.
How to migrate?
For dummies:
1)
How to get Lazraus best into my Linux-VM?
The app-lists of my Linux overwhelmed me. There are hundreds of items, which I do not need.
What I need, I cannot find. And I do not find Lazarus.
2)
How to work with Firebird? My Linux offers me version 3.0.
As I work with 4 now, this will not work too fine.
I rather thought of changing to 5. How to do best?
Shall I upgrade Lazarus and Firebird together or each after the other?
3)
How to migrate my Lazarus 3 with all the components?
There is eg. IBX, TVplanit.
Will they work with 4 at sudden?
Or shall I just wait 3 months more?
4)
Is the code expected to migrate easily from 3 to 4 or is there anything which needs adjustment?
And last not least, I want to sort my environment better.
What do you think about this plan?
I do not like it at all. In Windows I would use c:\programs for the IDE, but there is no such a thing in Linux?
$HOME/
├── IDE/
│ ├── lazarus/
├── Komponenten/
│ ├── myKomponenten/
├── Bibliotheken/
│ └── units/ ← Allgemeine Units (z. B. string_helpers.pas)
├── Ressourcen/
│ ├── icons/ ← Icons, Logos etc.
│ └── fonts/ ← Schriftarten, evtl. später Audio, Video
├── Projekte/
└── geteilteDaten/ ← shared data