1. No. Each ship, within its role, would be as capable as most other ship within its role. More or less. We don't need absolute parity, but enough to avoid complete obsolescence.
Why avoid obsolescence? Cargo haulers aside, we're talking about
one single ship in the game - the Eagle. And it is part of Elite lore that the Eagle is obsolete anyway.
The Eagle is a proven combat fighter with a distinguished history. It is one of the smallest fighters available with jump capability. It has the distinction of being the only ship that has been so successful versions have been built for both the Federation and Imperial navies. This role has been superseded by the respective navies' short range fighter programmes, but the Eagle still sees extensive service across human space. Core Dynamics are no longer building these ships, but do still provide parts and servicing due to their popularity.
If you think the viper, cobra, asp, FDL, vulture, anaconda, python, clipper, dropship, et all are obsolete then you've got to look again. The Eagle has a purpose as a trainer, teaching new players how to buy, outfit, balance, ships as well as how to deal with insurance and enter basic combat.
5. Good gracious. FD should hope and pray that their game is as popular as World of Warcraft was at its prime. It was, and perhaps still is, an unquestionable financial and commercial success rivaled by few and sought by many. THAT BEING SAID, it would take a lot more than "customizable ships" to turn this game into WoW, because if that were all it took then this game is basically already WoW anyway. Nevermind the fact that customizable ships are the opposite of classes, you dork. What we have now is more akin to classes. Customizable ships would be more akin to Ultima Online. Lastly, this isn't what I suggested at all, please practice reading comprehension.
It worked for WoW because that took place in the fantasy world of Azeroth. What you're suggesting is to start bringing magic into to sci-fi world of Elite. Seeing Eagles haul tonnes and tonnes of cargo, cobras refitted as capital ships with plasma weapons, and nimble anacondas outfitted as light fighters would completely break all immersion and roleplay elements of the game. As far as the universe and lore of Elite goes it would be Elite: Joke.
The Scope of my suggestion is basically this: Allow cheaper ships to fit expensive modules that let them perform somewhere in the ballpark of their more expensive cousins, maintaining price-performance ratio. It would probably boil down to tougher shields and a bigger power plant or distributer but whatever, not my job to dig that deep.
Well dig that deep now. I've already explained why this fails on immersion and roleplay elements, let me explain why it is
even worse for gameplay. Let's consider another game, an arcade style arena shooter with vehicles. The sort of game where this might work; World of Tanks. Imagine implementing this sort of thing on that. Don't like the fact your Maus is so slow? Just drop all the armor and fit a great big engine! It can zoom around but because you've dropped the armor its still balanced. Hey, my Object 704 tank destroyer can't shoot things behind it. I'll just take the gun out and put a turret on...
Now what has happened? When people drive out into battle, and see enemies, they've no idea what they're going to fight. That maus could be a well armored but slow behemoth, or could be a pew pew pew tank. And that T-34, ohhh no, why does have a cannon the size of a tree on it? And where is it's turret?! Tactics, thought about how to deal with the various tanks when you face them.
Back to Elite; so I'm zooming along in my FDL, and I'm jumped by a trio of Eagles. Ok, I hope they're not spectacular pilots but even if they are this thing is grade A, I should be able to take them on. WHAM! In comes 2 large plasma shots and huge missile, ohh and for some reason they have managed to fit C3 beams, stripping the shield as that missile is on its way. Now as I explode in space, I have to look at the entire range of ships in a different light. Any ship could be anything. There are no longer roles for them. Tactics on how to deal with ships, ideas on how best to outfit them and how best to fulfill the role and match it with your own skillset, all gone.
Even on a gameplay level this idea completely fails. It would change Elite from being an immersive roleplaying space game into basically being a badly made and ill thought out Unreal Tournament mod.