This is probably a rather stupid question, but like I said I’m very new to the pedal world...
What’s the difference between/advantages of isolated outputs and non isolated?
Isolated means that each output has its own transformer and they don't share the same ground reference. The advantage is that this helps eliminate noise, the disadvantage is cost and weight.
You may or may not need isolated outputs. If your pedals have a similar impedance, you most likely won't need it. I used to have a Voodoo Lab Pedal Power 2 for my large pedalboard, then I realized all my pedals were similar (all analog, low current draw). I daisy chained them with a one-spot and noticed no increase in noise, so that's what I use now. However, I know for a fact that if I introduced a totally different pedal in the mix, noise would be awful with this same setup (I once tried to insert a Source Audio programmable EQ pedal - Digital, higher current draw than my other pedals, and the noise was terrible). So it really depends on what pedals you plan to use.