There are multiple ways of increasing beam and kinetic range. Beams can outrange missiles with enough, kinetics cannot. That's why you get shot. Battle positions are fixed, it cannot place anything in default beam/kinetic range.

To the original poster... check out the wiki page and "ship roles."  If you don't want your missile boats being shot at right away, assign them a different role.  Put your missiles on yor capitals and guardians, give your guardians a few boosters so they can quickly find range, and there you go. 

I think the set up is actually pretty good.  Right now, you have the option of deciding in what line your weapons are placed, and what they will target, due to the ability to assign roles.  You just have to fight through the escorts first, but if you didn't, then the game would need the AI to armor up the capitals, which would then effectively be escorts.

You could give the player the ability to task specific targets to ships, such as designing a ship that goes after the highest missile threat first, then the highest beam threat, and so forth.  And tell a ship to keep at maximum range, thus being able to move backwards (which would also make thrusters more important btw).  But then every ship is going to be balanced with armor/weapons.  Which is fine, I guess.  And most ships are going to be moving directly towards the capitals, as they will tend to be the biggest guns.  Which means you will also want to be able to assign defensive/protective roles to ships.

Which we can already do.  It is possible that what you are heading towards is what we already have (aside from the lack of the ability to retreat to maximum range), although what we have may be what you are heading towards in its simplest form.  The biggest problem to me is how hull size affects role for the AI, rather than capability.

Yes, size affects role, which means that, for the AI, size affects starting position and targeting order.  Interceptors are tiny.  Guardians attack Interceptors first.  If you want to be able to have your low-damage, rapid-fire missiles go after tiny targets first, make them Guardians.  Although, really, almost everything in your fleet is hitting the tiny targets first because the tiny targets are in the front of the enemy fleet.  Which is why I think the size/role relationship is an issue.  Imagine if the AI put a couple of huge hulls up front loaded with Missiles with 100% armor take down.  I hate to say it, but maybe a few different approaches to fleet formation should be written for the AI, and the AI factions randomly get assigned one at the beginning of each game.

But ultimately, for now, I think its already possible to do most of what you want done.

If a change is made, maybe include a part that doesn't depend on a rare resource that can provide protective cover to ships behind it or near it.  Then the player would have a strong reason to target the escorts first, if the escorts are shielding the capitals, rather than just being forced to target the escorts.  Anti-missile turrents and such.  And also the 'stay at maximum range' thing, which isn't the same as what the Support ships currently have.

Also... I believe the Interceptors race forward because they are trying to get Guardians in range, their preferred target.  Once any Guardians are in range, they should stop moving forward.

There's a few basic issues with the current system that bug me most, tbh:

a) The AI doesn't really understand fleet composition. This has improved a lot since the addition of AIFleetGovernorDefs.xml, but it's still not great at getting a good mix of roles due to the mis-match between the AI roles (what the AI perceives a ship to be) and the actual role (the thing you can designate in the designer). The AI builds fleets out of AI Roles rather than actual roles... and the assignment of these is not particularly well considered. For example, a Yor Dreadnought (capital ship role) is considered an Assault ship by the AI... as is the Prototype Defender (Guardian Role).  These two ships behave completely differently in combat, yet when constructing it's fleet, the AI will use them interchangeably.

The AI also doesn't really understand real roles at all, and so always uses the default role on a ship. This is crippling when they player can set roles manually. I'm honestly not sure why the ability to manually set roles was added tbh; it's just begging to be used exploitatively, as we can set ships that are clearly of one type to behave and be targeted as if they were quite another. Setting all your attack ships onto Guardian or Support, for example, means that they'll target the enemy's non-capital DPS ships first and everything apart from interceptors (which are invariably weak, individually) will give them a very low priority. This allows you to mince most 'fair' fleets by rapidly disarming them as they pound your escorts, and then sweeping up once they have no DPS.

c) Frankly, it just feels ludicrous for an entire fleet to insist on shooting an unarmed ship with nothing but armour, shields and point defense rather than ignoring this unkillable ship and going for the heavily-armed, poorly-defended ships that are behind them. I don't object to target lists, but the whole concept of the Tank Ship is silly since no-one in real life would bother to engage it. They'd kill the highest threat first rather than the highest fortitude.

The whole thing seems to work upside down, tbh. Ships go out of their way to be intercepted by defenders, rather than trying to achieve their actual objective (i.e., kill the targets their armament is best suited to - rapid fire vs fighters, high damage per hit vs capitals). Escorts should attempt to destroy ships that are trying to kill the target their protecting, but they shouldn't be high-priority targets in themselves (for most ships). 

Oh, ignore the viewer. It's almost always out of sync and has nothing to do with the results (often to the point of announcing the wrong victor, let alone just wrong kills or incorrect firing order). If you're seeing the enemy fire first in the visuals, it's irrelevant. I've pretty much given up watching because it just slows you down and the visuals are meaningless. The combat log is the only accurate thing.