a)you only upgrade existing one to second existing one (e.q. laser to turbolaser, red strelka to white strelka) - but this is all.
b)each weapon can be uniqely upgraded (each upgrade is defined in wepons data) - and levels of wepons vary from weapon to weapon (e.q basic laser can be upgaded 5 times, and higt-texg e.q. QAC one times, or not) - and upgrades of weapons can vary from improving ROF (rate of fire) to damage, and special effects (like adding little chance to shut-down shield, shield/armour -piercing capacity..etc).
c) booth combined

2.more starting ships - locked - you need to complete game to unlock new ships (and one hidden if you complete game with all 3 types), the same for devices.
3. advanced battle arena - in this are are tournament - you can sign in (but only if you are proven warior - win first arena and mayby done another tasks) and you can bet (and look at fight, can be skipped) on winer of competition (of one battle, runer-up..etc) - e.q. from 32 gladiators can be only one champion,one tournament per year (2? hours of real-time) with radio/board messages how much time remaining. you can bet on single fight/runer-up/champion of yours competing gladiators - and most important - you cant die here, you only pay moneys for "resurecting".
Firts prize - good anti iocrym weapon, but bad non-iocrym. Repairing (limit on mey can be spend on repairs) during tournament is limited -and this count for booth you and competition.
4. hull - in curent game if yours armour are gone, then one hit to non-protectd side - game over. And this is bad, it will be nicer if you have "second chance" with hull, and after hull is destroyed, then game over. (and yes, this make sense for armour weapons proposed by me , you can destroy enemy ship, while they have good part of armour).