The gnote forum here is pretty quiet, xda has a more lively one.
To answer your questions,
Can this be permanently unlocked via an Android App, that can survive ROM flashes for free?
It can be permenantly (sim) unlocked via an app for free, I did mine when i first got it, although the app I used seems to have been removed from the play store, possibly because it only worked with gingerbread. This one https://play.google....z.galaxysunlock
should work with ics/jb, I havnt tested it myself though.
Whats this Yellow Triangle, can it be deactivated for good via Android App?
I think the yellow triangle is the result of a sort of counter that logs how many times you flashed something onto the phone, do it more than a few times and it appears. There are apps and tools that get rid of it permenantly and most custom roms wont trigger it anyway, so its not really a problem.
Can you flash any ROM you like via a Recovery Manager App (like CWM), whats all this ODIN about?
Odin is only used for the initial rooting/flashing, and there are other methods that dont use it. Once cwm is installed you can flash everything from there.
Can you permanently brick this device, or is there always a way to restore/recover it...?
The only way to brick it is to flash an unsafe kernel, or, if your unlucky, factory reset on the stock firmware. Its due to a dodgy bit of coding on Samsungs part. There is an app called `got brickbug` that will tell you if your handset is one of the batch affected. All recent custom roms have the emmc command (the bit that buggered it up by calling a broken function on the NAND chip) disabled in the kernel, so they are safe to flash. Basically, do not wipe/factory reset anything until you have installed a safe kernel as per one of the rooting guides on xda.
Apart from that, as long as you dont destroy the bootloader, its recoverable.
Why do I see loads of posts about Sim Tray, do they break easily?
Never had a problem with the sim tray, iv never had to swap sims though.
Any other things I should know about...??
One thing that has niggled me is the lack of notification lights. There are some hacks to strobe the softkey lights, but i have never been able to get them to work, probably due to rom/kernel.
I love my note, its a fantastic device, the screen is a good size for browsing the web and its amoled like the blade, so its got those lovely vibrent colours as well. The 8mp camera is pretty good and the stylus is a nice extra, although I rarely use it. Im using the pacman jb 4.2.2 rom at the moment and so far its been very stable and impressive performance wise. Like the blade, there is a lot of rom development for the note, and its capable of running the latest Android version very well indeed.
Hope this helps.