My question is: Are there naming conventions I should be aware of?

I ask this because I just ran in some trouble because I - and I tested it - forgot to name one my subtheme files with a capital P (as in HomePage.ph versus Homepage.php). This resulted in the following error - but the error is now resolved:

[Warning] Unknown class passed as parameter
GET /s/dev/build

Line 420 in /Applications/MAMP/htdocs/s/sapphire/core/Object.php

This was not very helpful, but ok. I first thought it had to do with the fact that I used Homepage for my class, or a field named about, antother named info.

It is case sensitive, so if your file name is Homepage, the class it contains must also be Homepage.

There is more to it, look here: http://silverstripe.org/general-questions/show/272491?showPost=272491