Re: Mandatory voting.
There's a bit of a difference between having some spare time on a weekday, and having enough spare time at the weekend to encourage those on the cusp of not bothering to vote. There is really no reason for elections to occur on a Thursday other than for the convenience of politicians.
Seeing as we haven't had an election on any day other than a Thursday for quite a while, it's kind of difficult to say how big an effect it would have on turnout.