I can only adjust the width of the images once added in AEM. I wish to adjust the height also but there are no resize options to adjust the height! I would also like to customize my templates/ page using my own css and is there any way to do that?
Look at this artilce - notice how we add CSS in a clientlibs. You can control that appearance of your site by using CSS like we show in this article:
Yes please refer the article as Scott suggested. You can adjust the component using CSS