Whatever icons end up getting used, they are going to have to be flat out incredible at communicating what they are. I'm a somewhat experienced novice at the game, by no means a noob, and here's what I'm seeing in the above tooltip, line by line:
Missile Frigate - RCIX, burns 200 energy, ship cap is 98
Heals? No health level is: 154,000/154,000 (100%), Armor: 300, Will burn a clock in 10 seconds, has a prescription for Missiles
Runs on a gas engine at 100 horsepower, has 44 beetle heads, Hull: Artillery, hits a bullseye at 10,000 yards, but will explode if closer than 4,800
Yeah, I'm being kind of a tool here. >D Point I'm trying to make is that there's enough to learn in the game already, and though the tooltips could stand some retooling (yuk yuk), using too many icons, even quite good ones, gives users another layer of abstraction they have to cut through to get the info they need.