Well, being a GIRL, and interested in the film business myself, I have some insight.
1. Whoever said Natalie Portamn should be Luthien was dead on. She's BEAUTIFUL, and i don't want to see Liv Tyler again, she's Arwen, not luthien...
2. As Beren, I think Colin Farell perhaps...He seems kind of Rugged

3. LOTR was done for a low amount of money, and this can as well, if we can find dedicated, experienced fans in the film business who would want to work on the movie offering their services for a little amount of money, then we could DEFINITELY pull this off.
4. The director, I believe, should be unknown, someone who wants to do their best job their first time, and will really put their heart and soul into it. I'm still very young, (14 actually) but I plan on becoming a director or screen writer in 5 years or so, going to one of the top film schools in the country. I would LOVE to direct this movie someday, but for me that's at least 6 years away... so someone else would be IDEAL if we were to begin this soon...
5. It all depends on who you know. If you know people who are experienced with CGI, or who are blooming film makers, hire them, because they aren't aloof and successful YET, and will take any job such as this with the highest respect.