The crank on that bike is a Nervar Sport steel crank and the dustcaps that are screwed in are made of aluminum and are very soft. It is common for aluminum and steel to bond together with corrosion over time and it might be that you have trouble removing those dustcaps. Before attacking with an allen wrench, you might want to apply a penetrating fluid and some heat either with a heat gun or with a torch.

The seat post that you will need will be either 26.4 mm or 26.6 mm. I've seen both on these bikes. I just measured one in the garage and it's 26.4 mm.

You'll need new brake shoes for the Weinmann center pulls. Cheapest that I know of that are decent working are the Dia Compe gray pads for less then $10 for 4 from Amazon. KoolStop Continentals in salmon colored will stop better, but they are more expensive and more prone to squeeling.

Can't see the chainrings, but sometimes the rings on the Nervar steel cranks will sort of dissintegrate with corrosion. Likely can't find replacements, but the crank is sort of low value anyway.

Fork steerer will have 26tpi proprietary Raleigh threads but all of these I've seen (three) have standard 24tpi BB threads.

Spoke protector is still on there so it might have the original freewheel which would have been 14-28 Maillard which requires the old style large diameter removal tool. They are uncommon these days, but you can probably scrounge one, or because of the low value of a Maillard 14-28 5 speed freewheel, the destructive method may be in order.

Derailleurs would have been Huret and the ones on these bikes were not bad when cleaned up and lubed. They shift well with a decent freewheel.

Good luck with it and have fun. As many people say, these things ride better than they should.