I noticed that several people carry a spare clutch cable, a accell. cable, and fan belt.

Being a newbie how do I know thease parts needs replacement?

And if I had the part would I really be able to change it at the side of the road??

If the clutch pedal drops to the floor, you need to replace the cable. If the gas pedal don't make the car go varoom, you need to replace the cable. If the gen light comes, you probably need to replace the belt.

Yes, they can all be changed on the side of the road, if ya have the tools. Alternator belt is not as critical if you don't have to use the lights. I've driven 5 miles back to the shop with a busted clutch cable, but when the accelerator cable goes, you don't!

for the clutch and gas cables, they go 'bang' and the pedal hits the floor.
for the alternator belt, the red light comes on, sometimes accompanied by the sounds of belt parts being flung around in the engine compartment...

driving without a gas cable is very difficult, but you should be able to manage driving to a safe place without a clutch cable. T-IV's are lucky in that they do not rely on the alternator belt for engine cooling, so you have much more flexibility on that one.

accel and clutch cable replacement can be done without luxuries like a lift but it is nice to be able to drive one side onto a curb or something. or have a GOOD PAIR of JACKSTANDS if you're using a jack to raise the car - DO NOT TRUST THE FACTORY JACK WITH YOR LIFE! you will require a small Allen (4mm?) to release the pedal board.

i've never done a /4 alternator cable so i can't say how easy that is - but i gather it's more of a PITA than really difficult - i do not know what tools would be required.

the point of having them in the car on trips is that if you can get yourself to a service facility, they can do the work if you have the parts - lots of places don't stock the parts we need.