Thank you so much! I'm going to try answering everything.
First of all the web version! Make sure you use Ren'py version 7.4, as for any older versions you can't create working files for web anymore. In the Ren'py main menu you will find "Web (Beta)" on the left side. It will create a zip file for you that you can upload here!
So about the camera movement... Actually I just move the image to give an illusion of camera movement! You can use transformation (ATL). Ren'py should have a tutorial game literally called Tutorial that comes with a lot of samples on how ATL works.
Basically what I do is that I just change the xpos and ypos of the background image in a linear movement to make an image move from one starting position to another end position. Sometimes I just use zoom to make the image smaller or bigger. It looks as if the camera zooms in or out if I make the movement very subtle.
The height of the text... Hmm... Do you mean how I changed the text height in the textboxes? Actually look out for the property called "gui.text_size" that is located in your gui.rpy file. There's also "gui.name_text_size" that changes the height of the name of the character. Just change the value and it will be adjusted to whatever you want.
If you have another question let me know!