As with any microcontroller, you'll need some kind of hardware interface to load the program code onto it.
Often, such interfaces also assume the rule of Debug Interface.
I have read that the 'PIC KIT 3' programmer/debugger is the easiest.
well, I don't know that one. But if it's this one, then its website says
The PICkit 3 is not recommended for new designs and no new device support will be added to it as of June 1, 2019. For new designs, please see the MPLAB PICKit 4.
And I'd argue that yeah, don't go for something that the manufacturer explicitly states desire to drop support.
Anyway, from the description:
Microchip’s PICkit™ 3 In-Circuit Debugger/Programmer
yeah, so it's a programmer and debugger. Check.
With the PIC KIT 3, is it possible to debug online in real time and see the status of I/O pins and registers etc?
That would be the purpose of a debugger. I doubt the both of us have the same understanding of the term "real time", because such microcontrollers run at megahertzes and you can't see that fast, but yeah, I'd presume that's the case, together with adequate software, which I guess the MPLAB X IDE is.