For 2, if a reasonable salary is $X, and the company offers you $X-$Y, you're essentially investing $Y per year into the company (at worse terms than actual investors). How much equity do/did investors want for $Y?
I do agree that for negotiation purposes, considering pay below market value is a good point for discussion. But don't get offended if it is not weighted as heavily as people who actually wrote checks.
If you choose a $90k job + equity over a $130k job, and the company tanks 2 years later, you've lost every dime of that 80k.
It's a bit different since your "investment" consists of 24 tranches, but that's more than balanced by the vesting schedule which gives you nothing for a year (despite accepting your investment immediately), and takes it all away if you stop investing.
Those are exactly the same thing. Pretending otherwise is asking startups to rob you.