Ok as I can understand R & D mode gives you root access to your device, make your keyboard backlight blink, show device info on the nolo boot screen and disable watchdog.
But how the heck should it be dangerous as all the warning says?(Other than accidentally deleting system files since you can be root)
Does the blinking light serve as a timer where once your reached the 1000th blink or something your n900 is gonna explode like an atomic bomb?
I really don't understand that warning that R & D mode is dangerous.

R&D Mode is dangerous just because it disables services like watchdog etc. which are important for your devices health. These services aren't developed without a reason.

only watchdog? I don't think it's dangerous to someone who has enough knowledge to enable R & D mode by himself? 0.o
I think nokia should have placed a proper description about that other than saying "do not enable R & D mode if you don't want to brick your device" like who the heck would want to brick their own device?

Can I post a new thread? I have some questions in my mind and I want to solve them before I buy N900.Thank you and I am waiting for reply.so please do me a favor.

Why would you ask me if you can post a new thread? You can post your own thread anytime here of course. Just go by the rules so it won't get deleted.

Hahahahhahhaha.
Newbies

Hey thanks for reply.
I did not know if I asked the Q to you,specifically.But you did answer.thanks.I could not find any link allowing me to post a new thread.
And its really not good that we have to find ourselves where we have posted our reply,there must be a link in our sidebar so that we can access our posts and replies.
Thank you very much,Radical.
Now please answer my Q,
When we compare N900 with laptop then we should be able to use our wifi connection on it.like in laptop with the help of 'internal router' we can access anywhere,without having to pay for new service when we move out of station.
If N900 does not allow this and can only be used as 'router' for your laptop.its really disappointing and I wanna decide if I should go for a laptop or N900.
Please reply as I want N900 asap!

Oh ya I am a newbie and not a techy guy,if techy or geek means 'developing software' I am not the one,
so please help me out.

The blinking lights are cpu/ssd (hdd) usage.

Same as how your pc lights blink for cpu/hdd usage.
You can disable these. I made a thread for NITDroid which has that in there.

I ran my phone for around 6 months in RD mode.
It also stops programs from 'force closing' if I remember correctly.

If you don't have a need to be using RD mode, don't.

Yes you can use wifi directly on your N900 like your laptop