At a seed round you want to raise the capital to assemble the team and to put together an MVP. That means that the more you pay yourself the less you have to execute on the other fronts and the additional risks that you are putting between now and the milestones that you need to hit in order to either break even or do a Series A. With that been said, I would stick to a low salary that is enough to pay your necessary needs.
Yes. In fact, I think it would be immoral *not* to try to cover the cost of living when seeking seed funding.
If you are burning your own personal cash, then you have to consider that in your funding.
Also if you are looking for funding, and the person involved isn't willing to allow you to pay yourself a basic salary, then find another investor. It's not going to end well.
VCs are money managers who don't want to pay you anything, they want to maximize their profit and don't really care about yours. If you need to draw a salary to survive, you can't found a startup that takes time start earning significant revenue. The trick is to design your operation such that it makes money on it's own, and doesn't need VC investment to survive. Once you hit that point, VCs will be falling all over themselves to write you a check. True story.
Yes, it is normal to take sustainable salaries. If you constantly have to worry about how to pay your own bills, you won't be able to dedicate 100% to the company. If you cannot dedicate yourself to the company, my investment is not safe with you.