Each one may only be taken once by any squadron or ship.
Tyranid Evolutions
the following are exactly like the original tyranid list except for the potential for escort upgrades:Solar Vanes - The ship or squadron gains +5cm speed. 10pts per capital ship and 5pts per escort
just like AndrewChristlieb had it Adrenaline Sacs - The ship gains +1D6 when on All Ahead Full special orders
it should be 10 and 5. IN grand cruisers get the upgrade for 5 points.Advanced Discharge Vents - The creature reduces the distance it needs to move before turning by 5cm. Not intended for escorts. 10pts
10pts seems right. This is a decent choice for 15cm moving hive shipsExtra Spore Cysts - The vessel gains 1 extra shield. May not be taken on escorts. 10pts
Accelerated Healing - The bio-ship has enhanced its ability to heal critical wounds, enabling capital ships to roll two extra dice in the End phase when attempting to repair critical damage. Not allowed on escorts. 10pts.
Drone Link - The creature maintains an unbroken link with the Vanguard drone ships and hive ships of the swarm. When within 15cm of a Vanguard drone ship, all pyro-acid batteries benefit from a left
shift on the Gunnery table (before all other modifiers). 20pts and 5pts per escort.
20pts like the old rules but making this available to escorts for 5pts makes sense. That will scale with the size of the escort squadron.Tenacity - When on All Ahead Full, Burn Retros, or Come to New Heading special orders, the ship's pyro-acid batteries and bio-plasma weapons are unaffected. The cost of this upgrade is 10% of the vessels initial points cost rounded up to the nearest multiple of 5.
AndrewChristlieb, your 10% and round up option for this upgrade is the best thought I have heard all day. You deserve a cookie. 
the following are modified old evolutionsPsychic Scream - Any enemy vessels withing 30cm suffer -1Ld. Enemy ships can be effected by multiple psychic screams at once, to a maximum of -3ld. This may only be taken on hive ships. 20pts
...like the old psychic scream was. good call on the max of -3 ruleReinforced Carapace - The ship gains +2 hits. Not allowed on escorts. 20pts
... just like the old evolutions but this restricts it to +2 hits ever.Mucous Membrance - Bombers and assault boats suffer a -1 modifier (in addition to any other modifiers) when rolling their Attack roll, and all torpedoes must roll +1 to hit (maximum of 6+). Ranged weapon hits remain unaffected. The cost of this upgrade is 10% of the vessels initial points cost rounded up to the nearest 5's digit.
I think we should use this pricing system because it is that much better on ships with more hits. Consider this on an adult hive.......Mega-Spore Mines - Ships equipped with assault boat launch bays can exchange all their launch bays for spore mine launchers. Each launch bay can launch one mega-spore mine In the Ordnance phase Megaspore mines follow all movement and ordnance rules mines do on p.142 of the rulebook, but when rolling against armour to inflict hits, it inflicts that number of fire criticals instead. Not intended for escorts. The launch bay strength is replaced by spore mine launchers at a 1:1 ratio. This also costs +5pts per launch bay strength.
5pts per is a much more appropriate value. Orks get mines for 5pts per in FAQ2010 and their ships are the same speed. Also, these don't get the benefits of double launch capacity so it's even with Orks. True, these are fire criticals, but normal orbital mines that roll a hit cause a guaranteed damage whereas spore mines cause fire crits that can be repaired. In the long run, these have the potential to do more, but I think it evens out, if not the spore mines being a slight bit worse, certainly not worth 10pts each. EDIT: when looking at the BFG:R list now, most tyranid carrier HAVE spore mines in them and there are special rules for them. Maybe we should just drop this and make the rules for mega spore mines into the rules for the normal spore mines tyranid carriers come with (the fire criticals damage instead of normal damage)newly invented oneNatural Killer Antibodies - The Fleet has evolved a more efficient Ordnance defense creature. Vessels add +1 to their Turrets Characteristic. +10pts per capital ship, +5 points per escort.
turret upgrades for IN ships are 10pts so 10pts for capital ships and 5 per escort makes sense. I think this could be dropped if the hive ships just had this upgrade built into their stats for the correct points. drop listHardened Myelin - The Fleet has increased the thickness of the myelin sheath around its dendrites, improving cognitive function. The vessel or squadron gains 1 re-roll, free of cost, that may only be used on that ship or squardon. 15pts.
this is exactly like the eldar farseers from MMS and they are 15pts. I think this should be dropped and added to the fleet list as Hive ImperativesPheromone Rage - The Fleet has evolved a more powerful Hive Mind, and is able to plan attacks more
efficiently. The Fleet’s Attack Rating is increased by 1. May not be taken in an allied Fleet and may only be taken on a Hive ship or any kind. 10pts
10 points. many people do not use attack ratings so who cares, attack rating does not mean all that much, and it will take up valuable upgrade points. this isn't a necessary inclusion. Maybe something that can be in the fleet list?Spore Cysts - The Fleet has evolved organs which release numerous spores, concealing the Vessels in a living cloud, and making targeting them rather difficult. The Vessels have the Holofields quality The cost of this upgrade is 10% of the vessels initial points cost rounded up to the nearest multiple of 5.
this is super fluffy to me and I think it will be quite characterful in game. Let's drop it in favor of the original +1 shield option.