Hi,
1 – no (you could convert all the images to custom icons but it would be very time-consuming)
2 – [mappress width="100%" height="100%"]. Note that if you set a % height your page body must also have a height. Most blog pages don’t (since they can be scrolled up and down). You can test it by just putting a div in your theme:
<div style="background-color: red; width: 100%; height: 100%"></div>