First of all, I want to ask a lot of related things, so I was lazy and wrote a question suiting my needs, which I can retire if it doesn't fall under the community's requirements. Please let me know by your voting/flagging.

Got a Dell OptiPlex MFF. It came with Ubuntu OOTB in a single partition in the 1TB HDD. I want to keep the OS but not regularly use it, and I also want to reduce the partition to add space to an NTFS data partition.

Not the main question though; I have added a 500GB SSD (no previous experience with them) where I intend to keep my main OS's for faster access if possible (Windows 10; a GNU/Linux flavor I'll be using most of the time; and if possible a third future OS, which will probably be another GNU/Linux or FreeBSD, whichever I wish to try out after experimenting with VMs). Leaving the remaining space for a data partition would be great too (not sure about the file system format for it; does talking about them make sense regarding SSDs?).

The SSD is visible in the Disks app but is not formatted. I suppose this isn't needed because SSD. Is that correct or incorrect?

The Windows and initial GNU/Linux .isos are in the HDD partition. I don't have any pendrives for boot drives, although I can certainly buy them if needed (I guess I should, for creating a recovery drive for the Ubuntu install as recommended).

What would be an straightforward, reasonably easy way of achieving all that? Basically what I'm asking is how to install two or three OS flavors on a secondary storage (SSD) from a HDD (which I'll work upon throughout the process).

First of all, I want to ask a lot of related things, so I was lazy and wrote a question suiting my needs, which I can retire if it doesn't fall under the community's requirements. Please let me know by your voting/flagging.

Got a Dell OptiPlex MFF. It came with Ubuntu OOTB in a single partition in the 1TB HDD. I want to keep the OS but not regularly use it, and I also want to reduce the partition to add space to an NTFS data partition.

Not the main question though; I have added a 500GB SSD (no previous experience with them) where I intend to keep my main OS's for faster access if possible (Windows 10; a GNU/Linux flavor I'll be using most of the time; and if possible a third future OS, which will probably be another GNU/Linux or FreeBSD, whichever I wish to try out after experimenting with VMs). Leaving the remaining space for a data partition would be great too (not sure about the file system format for it; does talking about them make sense regarding SSDs?).

The SSD is visible in the Disks app but is not formatted. I suppose this isn't needed because SSD. Is that correct or incorrect?

The Windows and initial GNU/Linux .isos are in the HDD partition. I don't have any pendrives for boot drives, although I can certainly buy them if needed (I guess I should, for creating a recovery drive for the Ubuntu install as recommended).

What would be an straightforward, reasonably easy way of achieving all that? Basically what I'm asking is how to install two or three OS flavors on a secondary storage (SSD) from a HDD (which I'll work on throughout the process).

First of all, I want to ask a lot of related things, so I was lazy and wrote a question suiting my needs, which I can retire if it doesn't fall under the community's requirements. Please let me know by your voting/flagging.

Got a Dell OptiPlex MFF. It came with Ubuntu OOTB in a single partition in the 1TB HDD. I want to keep the OS but not regularly use it, and I also want to reduce the partition to add space to an NTFS data partition.

Not the main question though; I have added a 500GB SSD (no previous experience with them) where I intend to keep my main OS's for faster access if possible (Windows 10; a GNU/Linux flavor I'll be using most of the time; and if possible a third future OS, which will probably be another GNU/Linux or FreeBSD, whichever I wish to try out after experimenting with VMs). Leaving the remaining space for a data partition would be great too (not sure about the file system format for it; does talking about them make sense regarding SSDs?).

The SSD is visible in the Disks app but is not formatted. I suppose this isn't needed because SSD. Is that correct or incorrect?

The Windows and initial GNU/Linux .isos are in the HDD partition. I don't have any pendrives for boot drives, although I can certainly buy them if needed (I guess I should, for creating a recovery drive for the Ubuntu install).

What would be an straightforward, reasonably easy way of achieving all that? Basically what I'm asking is how to install two or three OS flavors on a secondary storage (SSD) from a HDD (which I'll work on throughout the process).

First of all, I want to ask a lot of related things, so I was lazy and wrote a question suiting my needs, which I can retire if it doesn't fall under the community's requirements. Please let me know by your voting/flagging.

Got a Dell OptiPlex MFF. It came with Ubuntu OOTB in a single partition in the 1TB HDD. I want to keep the OS but not regularly use it, and I also want to reduce the partition to add space to an NTFS data partition.

Not the main question though; I have added a 500GB SSD (no previous experience with them) where I intend to keep my main OS's for faster access if possible (Windows 10; a GNU/Linux flavor I'll be using most of the time; and if possible a third future OS, which will probably be another GNU/Linux or FreeBSD, whichever I wish to try out after experimenting with VMs). Leaving the remaining space for a data partition would be great too (not sure about the file system format for it; does talking about them make sense regarding SSDs?).

The SSD is visible in the Disks app but is not formatted. I suppose this isn't needed because SSD. Is that correct or incorrect?

The Windows and initial GNU/Linux .isos are in the HDD partition. I don't have any pendrives for boot drives, although I can certainly buy them if needed (I guess I should, for creating a recovery drive for the Ubuntu install as recommended).

What would be an straightforward, reasonably easy way of achieving all that? Basically what I'm asking is how to install two or three OS flavors on a secondary storage (SSD) from a HDD (which I'll work upon throughout the process).