Anti, this is incorrect on a few egregious counts.
Normal handguns only deal 1d6 damage (for those of you outside of the know, thats a standard six sided dice rolled for damage once) and advanced pistols deal 2d6.
Not even true in the 9.8.5 release; normal pistols deal 2d4 damage, while advanced pistols deal 2d5 damage (in the beta, both types deal 2d4 damage).
Pistols only become a serious weapon when SoaG (Son of a gun: +2 pistol damage) and SoaB (Son of a b**ch: +1 damage in general) reach level 3 (the highest trait level), one level of Dualgunner (enables dual wielding of pistols) and many weapon mods.
Not quite. You definitely need SoG to make the pistol worth your while, but I don't remember ever taking SoB in any of my AoMr games (at least, definitely not before Fin). Plus, SoG is
not just extra damage, it also reduces firing speed by 200 energy per level (where your normal firing speed is 1000 energy, meaning that at level 3 of SoG you only spend 400 energy to shoot things). Finesse actually seems slightly better than SoB as well. Let's say you've got two characters, both with SoG 3. One has Fin 2 in addition, while the other has SoB 3 in addition (to the SoG 3). They're both firing 1 pistol. The guy with SoB 3 is shooting 6 shots that deal 2d5 + 9 damage, or in other words 6 shots that range in damage from 11-19 (average damage being 15), at an energy cost of 400 per shot and 2400 energy total to empty the whole clip. The guy with Fin 2 is shooting 6 shots that deal 2d5 + 6 damage or range from 8-16 (average damage being 12), at a cost of 200 energy per shot and with a total of 1200 energy for the whole clip. Now, the player with SoB 3 will do on average 90 damage with a full clip, and only end up spending 2400 energy. This is great if you're only taking on one enemy; according to the wiki information you could even [barely] take out a Vile with this setup (armor is taken into account too) before needing to reload. Compared to the measly 72 damage the guy with Fin 2 gets, this seems like a sweet deal. But consider this: What happens if you miss, or simply find you can't take that enemy down with one clip? The Fin 2 guy gets the chance to reload, and takes just as much energy as the SoB guy has simply shooting. Plus, the Fin 2 guy has a spare level, which he could use on DG 1; this'll make him take 280 energy to fire, but he gets an extra 8-14 damage that raises his average damage from that measly 72 to 138, and his total energy cost even with the DG penalty is only 1680 (for reference, it takes normally takes 1000 energy to fire once, move, or heal; it takes 1200 energy to reload). Add on to this one of the special advanced traits in the beta (which makes spoilies even better) and I rather think Finesse is the winner.
I don't know how much in the way of hitpoints the Cyberdemon has, nor armour so I cannot give you the average number of bullets required to defeat him.
According to the wiki, Cybie's got 200 HP and has red armor level protection. So if you managed to trick out your character with 3 SoG, 3 SoB, 3 DG, and 2 Fin, assuming average damage and non-beta it would either take about 16 bullets (8 shots per gun; two guns) plus an R after the first 12 run out (average damage = 15((2+10)/2 + 9) + 14((2+8)/2 + 9) = 29; 29 - 4 = 25, 200/25 = 8) for a total energy cost of 5600 (16 * 200 = 3600 + assumed R = 2400 energy), or about 17 bullets (first 12 shots coming from both guns as before) plus an r after the first 12 are fired (first 12 shots do 150 (25 * 6) damage to Cybie, last 5 do 11 damage (15 - 4) each, leaving Cybie at -5 HP on the last shot) for a total energy cost of 4600 (1200 + (17 * 200)). Actually, now that I look at it it seems like the single reload wins this bit (actually, it still does even if you're able to get Reloader 2; the only way you'll ever beat the single reload with two guns is if you find a fastload pistol for the second slot, and even then you'll need at least Reloader 2 to make the dual reload faster than the single reload).
Another reason why it is a pain to kill the cyberdemon is that most weapons at and above the level of the Chaingun are a far better choice to kill the beast with.
I wouldn't say that chainguns are really a lot better than the pistol; assuming you have Int 3 and thus can always hit Cybie even when he's out of range, the math looks like this: Because Cybie basically has permanent red armor, chaingun shots practically bounce off of him (even assuming the minimum damage is 1, that still means that the damage range is 1-2, practically as bad as trying to punch Cybie to death [6-4=2, and that's the most an unmodified chaingun can do!]) unless you have some SoB, and even with SoB 3 the damage range for a chaingun is still reduced to 4-20 (average damage: 12). In comparison, a pistol user with only SoG 3 gets a damage range of 5-13 (average damage: 9) and uses 600 energy less to fire. Not as much damage, but a lot more time to react to Cybie with the same number of traits. I won't disagree with you on the subject of the BFG or rocket launcher though...
1d5*5 per chaingun salvo will produce anywhere between 5 to 25 points of damage WITHOUT any feats, each shot gets its own chance to hit so on the whole it will hit more often.
Incorrect. It does 1d6*5 damage, and each shot also gets individually reduced in damage by armor (which means if you meet a human commando [naturally gets two levels of TaN] wearing blue armor, you'll be doing 1-2 points of damage per shot) as mentioned above.
The rocket launcher deals 3d5 points of damage (correct me if I'm wrong. I'm only quoting from memory) with a blast radius of about 5. This means you can hit the cyberdemon even if you miss as blast damage is pretty much unavoidable.
Rocket launchers deal 4d4 points of damage, not 3d5. And if there are no walls nearby you won't do any blast damage to Cybie.
Plasma rifles and BFG9K's are the most powerful ranged weapons in the game and deal a ton of damage. I think plasma rifles do something like 2d6*6...
Like I said, not gonna argue on the point of BFG's. However, plasma rifles do 1d8*8 damage. For the record, BFGs do 8d8 damage.
Which brings us back to the humble pistol - Usually the weakest weapon in the game.
No. Weakest unmodified gun, perhaps, but not weakest unmodified weapon.. the knife/fists fit that category at 1d6/1d2 damage. It also gets some very, very nice traits to balance it's initial weakness.