1. Which passages are you thinking of which seem inconsistent? I don't know that the experiences of Merry and Pippin even factored into my argument at all.
Tolkien Profesor stated thet the switch between pure evil orcs and those "free-willed one"s in LOTR is between the orcs Merry and Pippin encounter and those that Sam encounters in Cirith Ungol. LOTR was written by Bilbo then Frodo and then Sam. But the experiences of Marry and Pippin can only have been reported by Merry nad Pippin, even if Frodo and Sam were thoe wrote them down. So there is a clear switch of perspective there.
2. Personally, I think you're making far too light of the counting game, and the underlying viewpoint driving it. It's not simply counting kills and seeing who got the most; it's the whole treatment of orcs as simply evil throughout the books. And it's not just a few characters; it's pretty much everyone throughout the entirety of Middle-earth. If the orcs are not completely and utterly corrupt and wicked to the very last member, then this view of them is itself inexcusably vile. And yet, if they are, then we're back to the earlier problems.
The counting game does not say anything about the orcs. It says far more about Gimli and Legolas themselves than about orcs.
3. People have played such counting games during war. People have also slaughtered and pillaged villages during war. The fact that it has happened in our own history does not make it right or acceptable.
Yes, exactly. It does not says anything about the "victims" of such a game. Only about the (sometimes willfull) ignorance of the people involved in it.
Projecting post-christian values on dwarves and elves (and especially Non-High-Elves) is imho an anachronistic aproach.
I do not think elves have an outward system of moral values per se in a set of formalised commandments and rules. Normally they would not need it. So projecting human rules and laws onto them is an error. As elves are basically "good people" they have less tolerance for evil than a marred human, who is avare of his own failures, would ever have towards another human. And Mirkwood elves are "more wild and less wise" then High Elves.
And the other books, who wrote them? Both the Hobbit and the Translations from Elvish ("Silmarillion") - Bilbo did. For Bilbo orcs serve more as an literaly device, he had no personal encounter with any which involved any kind of direct interpersonal interaction.
Orc being orc move inside their own spectrum and have to make they choices to make inside that frame as any other race has too, e.g. the Easterlings.
They role inside Middle Earth is giving face to the results of corruption and evil and as such making it obvious what Morgoth and later Sauron really are about, even when they still look preety, orcs are the fruit by which they can be recognised. As such orcs are a vital witness to the other races why they have to resist evil if they do not want to end like them.
I do not think orcs are dammed to "hell". There is The Void, but I do not think all orcs' spirits actually end there. Do not think an orc's spirit's fate is much different to an Avari's or even Silvan elf's who refused the call to Mandos.