Okay, I'm really new when it comes to SW:ToR and most of SW as a whole. I did see the 3 original movies back then in the cinema, and I played only one SW-game long ago (Jedi Knight). So when it comes to most of the SW franchise I'm a real newbee ;-)

Looking on the SW:ToR site I was looking what class to play. The sage/healer advanced class does seem like my style, and I want to give it a try. But looking at light/dark side skills, there is quite some difference. Where the Inquisitor Sorcerer shows an AoE heal over time, the Imperial Sage has a stronger 1-player heal over time, as well as a resurrection skill, which I missed on the Inquisitor Sorcerer completely.

I also looked at other classes, and there are quite some differences, where light seems more healing & subtle vs dark being blunt and massive. Am I right in this assumption?

I was also wondering if there's already a (better) skill list than those 6 skills shown on the SW:ToR site so I can compare skills more before I shoose light or dark side.

The abilities on the website are simply a sample, I recall a dev mentioning there were about 30 abilities per class. Hope that helps :)

Each class basically has a mirror on the opposite faction.  So the Sage and Sorcerer are essentially the same class in terms of their abilities, the difference is essentially just aesthetic and flavor differences (a Sage isn't going to blast someone with Force Lightning and a Jedi Knight isn't going to force choke someone, but they will have a similar ability with a different name and graphic).

Each side has their mirror class. But there are differences. They won't play exactly the same.

For example from what I've seen:

Smuggler Scoundrel stealth tree uses blaster/scatter gun.

Imperial Agent Operative stealth tree uses melee blade.

Aesthetically they're different (like blast pistols for gunslinger and sniper rifle for sniper) but they function exactly the same.

In general, they are the same however there will be nuances to each side which make them different.