Thinking of starting Fluval edge 6 gallon nano

Completely depends on what you're trying to do. Low requirement plants vs high requirement. Find the plants you like, determine their requirements and go from there.

I believe the 6 gallon comes w/ a 3watt led (it's terrible) vs the 12 gallon's 5watt led (still terrible). You can buy the 5 watt on ebay and swap out the 3watt but there are much better alternatives. (FYI - wpg (watts per gallon) isn't a good way to measure lights, but knowing above might help your research.)

Let me know if you have any questions, I went fairly high tech in mine.

Lots of us have them. You will need additional light, you have to decide if the unique tank design is worth the extra effort to maintain it (small opening). You will need an algae magnet to move bubbles off the ceiling to the opening. Oxygenation and evaporation is more of a concern than normal. I wouldn't recommend it as a first tank.

I've had many fluval edge tanks, and currently have 2 of them just sitting around collecting dust but they're my next projects once I've finished planting my 45 gallon tank.