At the risk of giving an opinion-based answer, your friend is mostly right. Lucas began by writing a synopsis of the story in early 1973, then started working on a rough draft of a script the next year. Lucas' first draft was a mess: the story was confusing, far too long, and incredibly boring; the characters were terrible and bland; the dialogue was leaden ...
In 2004, Lucas released his Director's Cut of THX 1138. There are no changes as big as making Greedo shooting at Han, but the there were still some controversial changes. Here a quote from The O.C. Wikia George Lucas article, Controversy section.
Changes Lucas personally made to THX 1138 for its 2004 DVD release further re-enforced criticism from fans ...
George Lucas wrote the story treatment for the entire saga alone and the script for the first film (relabeled A New Hope) was a solo effort.
You will find Wookieepediaa far more reliable source than other wiki pages, as the information is highly scrutinized and verified by reliable sources.
According to the New Hope page:
• In January 1973 Lucas began ...
As you mention the allusions between Tahei & Matashichi and R2-D2 & C-3PO seem to be the most obvious, but the way the film is cut/executed is also similar.
“The one thing I was really intrigued by was the fact that the story
was told from the two lowest characters. I decided that would be a
nice way to tell the Star Wars story…That was the ...
It seems he took references from all religions and amalgamated into the movie.
From Bill Moyers' interview with George Lucas,
Bill Moyers: Have you been influenced by Buddhism, because “Star Wars” came along just about the time there was this growing interest in America in Eastern religions, and I — and I notice in “The Phantom Menace,” the new Episode ...
I don't believe there is a connection.
George Lucas has spoken about his inspiration for Jar Jar Binks, at the D23 Expo in California:
I can't even begin to tell you how much of an influence Disney has had
on me... I will say one secret that nobody knows; not many people
realize that Goofy was the inspiration for Jar Jar Binks… I know that
you will ...