These were failed attempts to create a smartphone at best. Most of them are high-end feature phones with more fancy features. Others tried to bring the desktop computing metaphor on a phone with a start button on the taskbar. A smartphone doesn't have tasks. It has fully automated process and file management otherwise it isn't a smartphone.
Tablet-PCs existed before and not as a niche, but as a failed and abandoned form factor of desktop computers with added touch-screens. These were not tablets.
No, companies like Blackberry, Palm, HTC, and Samsung were all making money off smartphones long before Apple entered the market. Treos, Communicators, Blackberrys were all market successes back then.
The definition of a tablet has evolved over the past decade. Used to be a convertible or detachable was considered a tablet. Now only slate form factor devices are considered tablets and convertibles/detachables are called hybrids.
And you're making up your own definition on what a smartphone is.
Anything pre-GUI is irrelevant for computers becoming personal computers. The command-line interface and its huge knowledge requirements made computers something for circles of experts, not for individuals to use them on their own.
CLI catered to the consumer market. And there weren't huge knowledge requirements. All you had to do was remember a few commands like "CD" and to run the file that ended in exe. Little kids were using CLI
The importance of the GUI is it made the interface more accessible, just like hardware commoditization made the price more accessible.