Is there any way of increasing the loudness of system sounds and alert tones?
I've got mine maxed out in settings, but I'm still finding them very quiet.
Thankees in advance.

Have you checked your ambience settings?

Same here, esp. the keyboard click sound is waaaaay too low.

I hope you guys are being sarcastic, because for me they are loud, especially when unlocking the phone :/

Nope. Everything is set up OK in my ambiances (Full volume for ringtones and system sounds.)
I don't think there's anything wrong with the speaker because videos and music play pretty loud.

Another problem I have is how do you clear the recent calls list? Haven't found a menu item to do that. If you use delete from within the list it also deletes the number from the contacts list.

Solved the problem of not being able to clear your call history. You can't.
Someone on Jolla Users asked the same question over there, he's got a year's worth of calls in his history. There's a script to run from x-terminal, but I'm not sure I wanna mess about like that at this stage. I used to run x-term scripts on the N900 but I need to learn a bit more about the Sailfish one.

I'm thinking of using mp3 files as ringtones etc as a work around.

What? If you delete items from call history it does NOT delete contact from phonebook.

Mine did the other day. Which is why I suspected that is what happened. I had to re-enter the contacts into my list afterwards.
Tried to replicate it just now but the contacts have stayed put.

you seems missed and used delete from contacts, not from calls

Maybe, but I'm pretty sure I didn't.