Asus N80 series questions, upgrading, sh1nigam1 is my hero!

You can just skip down to my specific questions right below the line I made and not read the intro background stuff.

MY LAPTOP: I have an ASUS N80vb laptop. This comes stock with Intel Core 2 Duo T5800 (2 ghz, 800 Mhz FSB - PGA478 socket, 35 w) and NVIDIA GeForce 9300m GS graphics card (8 stream processors, 4.6 billion texture fill rate, 13 w).

Now for my info. Only like 2.5 years ago, I was a strict console playing guy (sony playstation) so I had my gaming fix satisfied with that. For internet and school needs, my dad's hand me down ancient desktop sufficed. I don't know the CPU speed on it, but it was in the Mhz range, maybe 800-900. It was also running on integrated graphics, but later 'upgraded' with an old, old AGP 3d video card my brother was going to throw out. Then about a year and a half, a year and 3/4 ago, I got my current laptop..it was heaven!! I had a supercomputer compared to what I had before! But now in recent times, my roommate had gotten me more into PC gaming and now, exploring more recent PC titles, (even in the 2004-2005 range) I am finding that my once thought supercomputer is now lacking.

So..I was then wanting to upgrade a few things. I knew NOTHING of computers being a console guy so I've had to do SO much research to understand many things. I head that upgrading laptops was very difficult/impossible, but thankfully, with this particular ASUS laptop, it IS quite possible and pretty easy actually!

http://forum.notebookreview.com/asus/344547-asus-n80vn-disassemble-upgrade-vids.html

I found that thread recently actually after having ordered already an ASUS 9650m gt (looks like I narrowed it down to the right one, shew! Don't worry, I also made sure it was for ASUS' 'novel' reverse MXM slot configuration as well).

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QUESTIONS
1) Is the N80vb essentially the same as the N80vn like in the thread mentioned above?? The insides look pretty much the same from the video and the only difference I can see is the 'novel' fingerprint scanner near the touchpad. I mean, is the only difference cheaper components? And that both have the same upgrade potential? My thinking is that all N80 series are the same, and that the v(insert letter here) is just different concoctions (different, cheaper or more expensive parts) put in to make some versions cheaper than the other. Is this correct??

2) How does one know the top video card one can put in? I emailed ASUS with that question and the response I got was: any NVIDIA 9m series should work, only issue is heat. However, I'm not so sure. Looking at the other N80 series (vn, vc, vm, etc..) the top video card I could find installed was the 9650m gt. Obviously with the 9650m gt only utilizing 23 w over the 9300m gs' 13 w, this difference is negligible which was the main reason I ordered it. If I were to have gotten the 9800m gt running at 65 w, wouldn't there be more problems than just heat? I mean, would the n80vb BIOS (PM45 chipset btw) even work with it even though it IS still part of the 9m series?? How does one know without buying it and trying it and potentially wasting one's money?
Would one have to upgrade the power supply for the laptop like one does when upgrading the CPU and GPU on a desktop if the 9800m gt were feasible??

3) The ASUS email response also told me the potential CPU upgrades I could do. They listed these: T9400/P8600/P8400/P7350/T5900.

The T9400 is the top one out of all the ones mentioned (2.53 GHz, 1066 Mhz FSB). However, in the thread above that sh1 did the upgrades for his n80vn, I noticed he upgraded it to the t9800 running at 2.93 GHz and 1066 Mhz FSB. The ASUS guy did not tell me that this was an option, however, doing more research, it's seeming that it is possible. First, the t9800 has the same FSB speed as the t9400, so no issue there, no danger of overexceeding. Second, it uses the same exact watts (35) as the t9400 AND my stock t5800. Third, it uses the same socket (PGA 478) AND my chipset is PM45 which IS apparently compatible with the t9800. WHY did the ASUS guy NOT mention this CPU even though it is clearly superior to the t9400?? Is it not compatible meaning there is some strange, obscure difference between the n80vb and n80vn? Or did he just forget? Is it useless to get help from the manufacturer and just better to do research on your own and ask on forums??

Thank you so much to anybody that can answer at least a few of these questions. I know they are a lot, but I am very inquisitive by nature and need to understand the why of something, and not just the how. Again, thanks in advance for helping a formerly computer illiterate understand a bit more.

-Charlius-