1)TEC have the strongest economy. If you look at Advent, they get trade ports with NO upgrades and a single system (last I checked) one per system version of refineries which take most of the tech tree to be really worth the build time. They are reasonably structure efficient, but are painfully weak compared to the rest. Vasari get trade port upgrades, but not refinery upgrades. TEC get cargo upgrades that boost both.
2)Kodiaks are in my experience, the ONLY ship that can effectively hit a smaller, fleeing fleet and decimate them before they leave. Do not underestimate mobility. Often you have to activate the power manually to use it when and how you want, but it's a small price for a very nasty power.
3)In a fair fight, ship to ship, no upgrades, without support craft, TEC are arguably the weakest race, and their cap ships can be ... lackluster. That said, their support craft are excellent, and as I said, maneuverability is worth a lot. IIRC, for a pure Kodiak fleet, you can even use the power to reduce overland reinforcement times, giving you a LIMITED piece of the action that has always been assumed to be Vasari only.
4)a good TEC economy should be able to safely operate at one level of fleet upgrade higher than it's competition (all other things being equal). That means you should be able to bring more total firepower to bear.
On a smaller map, TEC are said to be a rush side. On a larger map, if you spend your time preparing for the 'inevitable' TEC rush (knowing your enemy is TEC), you may find they go for a fast overwhelming economy and just bury you with it.
Having said all of this, the cadence of a multiplayer game tends to be such that the crushing TEC economy does not often get a chance to stagger from it's knees before getting beat down by an LRM rush, and TEC are not at present my faction of choice... but there is what they DO have going for them (other than their support craft, and preference in support craft is highly personal and down to taste)