Hi James, welcome to the forum. Yes they drive the alternator and waterpump. The timing chain is situated at the back of the engine close to the bulkhead, and is only accessible by removing the engine.
The engine crankshaft (driven by the pistons) powers the timing chain at the back of the engine, which then turns the camshaft (which does the inlet & exhaust valve-opening work). On a R4 (my 1108cc version at least) the camshaft then shows itself as a pulley at the front driver's side (in the UK) of the engine, where a rubber belt drives the other bits you see (coolant water pump and alternator).
It's a long chain of events (ha ha!), but can be used to find out whether the timing chain is slack (meaning that the chain is worn out, or chain tensioner has a problem). With the engine OFF, if you can turn the camshaft pulley back and forth an obvious bit without the flywheel turning at all, then the chain is probably slack for some reason, as above.
Taking the engine/gearbox out is simple compared to modern cars, and quite therapeutic I find ! My timing chain tensioner was seized, leaving the chain flopping around loosely due to a Renault garage specialist failing to engage his brain when renewing the chain. Being a specialist in nothing whatsoever, I did it properly myself.
Yes, indeed there was a periode with timing gears, how careless of me...
The early models had 100% timing (distribution) gears untill the year 1964.
From 1964 untill 1971 this was modified by a double timing chain aka the duplex chain.
After 1971 this was modified to a single timing chain.