The 10F is so small it's not a good choice to learn on, choose a larger one instead - 18 pin devices seem a good starting point.
If you're going to use a 10F in a project, it's common to use a larger device for development, then swap to the 10F once you've got the design pretty well finalised.
As they all run pretty idential code it's not much of a problem.
I agree with Nigel. Having some spare I/O pins makes tracing faults in your code easier. You can check that the code is following the path you expect by inserting a few lines of code to pulse a spare output pin. This can flash an LED or can look at the pulse on your oscilloscope. This is paticularly usfull when you run your code and nothing seems to happen. you can insert the few lines of code to flash the LED at various points in the code to see if it actualy gets that far. With the scope you can also check how long sections of code take to run. I suggest avoiding the very recent PICs such as the PIC16F18446 as so many pins can be re mapped for different functions and this is confusing at first.
No, because it's not - there's too few pins to make it easy to use.
The code is no different, so a bigger one is no harder - and it's MUCH easier to learn because you've got free pins to play with, and particularly ICSP and debugging.
I find the 16F1827/47 an excellent choice - a reasonable compromise between the older devices and the newest ones.