My apologies for not responding to other threads that you have commented in. I'm always busiest this time of year and will try to reply properly to you when I have the time. I must reply to your interesting questions here.
1. I'm afraid, this one, would take quite a bit of time to paint you a good picture. I can give you resources, written by others that I believe are good references...Humphrey Carpenter's Biography, Tom Shippey's
Author of the Century, JRR Tolkien's
Letters. I can only recommend them as good resources that were often discussed on the OP. I've only read
Letters (and definitely not all of them). The general impression I get is, he was a 20th Century author (more on that in question 2) with a 19th Century sense of morals. I think Hobbits and The Shire tell something about Tolkien, the man. It is full of anachronisms, it all feels rather idyllic, pastoral, and nostalgic. It is not a medieval setting, nor a faerie setting. There is tea-time and waist-coat buttons, pocket-handkerchiefs, clocks...etc. The Shire is purposefully made to feel like "home" to us. I'm not sure what that tells, but it should reveal something about the author. Whether he was writing purely out of nostalgia creating a community that enjoyed things like him, waist-coats and pipe-smoking? Or he was trying to connect to 20th Century readers with a recognisable "home" before plunging into a fantasy epic?
2. This one I may be able to help more with, because I'm currently reading John Garth's
Tolkien and the Great War. It might be of interest to you? It's not really about World War I, but how WW1 effected Tolkien's writing. Now, Tolkien, many times, denied he wrote allegorically (and I believe him). But he also writes that an author can not be wholly unaffected by his experiences, and specifically mentions being caught in World War I's horror (by the end of the war, Tolkien wrote "all but one of my close friends was dead" - The Foreward to LOTR). What I particularly like about Garth is he also looks at Tolkien's developmental years in King Edward's School and within the TCBS, (Tea Club, Barrovian Society). Two of Tolkien's friends in the TCBS died in the war and that grief stayed with Tolkien his entire life. I haven't finished it yet, but it's interesting to me the dreams of schoolboys to write a literature that would profoundly influence 20th century readers. Garth does an excellent job connecting the dots to how WW1 (and its horrific industrialization) shows up in Tolkien's writing. (Frodo's PTSD, the Dead Marshes, Sam's first encounter seeing a dead Haradrim soldier, as some quick examples).
Another thing that I find interesting is the trauma of experience WW1 is present in Tolkien's writing, but I think Tolkien goes a different route than some of his friends and contemporaries (CS Lewis or TS Eliot as examples). Tolkien doesn't write this fatalistic, grimdark fantasy. Evil will always continue to manifest itself in different ways, but a core theme (at least for me when I read it) is Tolkien telling me to not give into despair. To always have hope (even when it's a "Fool's Hope"), to work together for a common good, and to as Elrond says "fight the long defeat."
3. I recall one letter Tolkien saying he thinks he would be most like Faramir. I'm not sure if there's anymore details, or if it was just a passing thought when responding to a letter.
@Romeran might know the specific reference.
Unfortunately, it's been mushed by the movies, as well, because I know "fighting the long defeat" line isn't in the movies. However, Elrond's line from the books telling Frodo if "he does not find a way, no one will" is given to Galadriel in the films. Some lines aren't in the movies, others are said by different Elves, I get my wise Elvish advice quotes mixed up.