I checked the antifreeze with one of those glass testers and there is practically no protection, the water was a light yellow colour.

The last owner was obviously not one for maintaining the Jeep - all the tyres were at 48psi when I checked them
Should I use red or blue antifreeze ?.

 

Colors of antifreeze doesnt necessarily designate what they are, I dont know about blue but most orange/red coolants are extended life but depending on brand they might be different types (OAT, HOAT) and have different additives.

You already stated the last owner was not good on maintenance, so what I would do is drain as much as possible from the system or do a flush and start over with a coolant of your choice. There is nothing wrong with green other than it doesnt last as long as the extended life coolants. Extended life coolants can be desirable for some people but I have no problem changing green out every once in awhile.

I guess I should have added, you Jeep should have came factory filled with regular green, pretty sure chrysler didn't use ELC until 2002 or so.