newbie question
 

Other than moving population around, what is the purpose of transports?

Also, is there a type of ship you can build that can travel with a fleet to keep the fleet supplied?

Re: newbie question
 

Transports are for carrying stuff. Population is not the only item useful to have moved around, of course.

Troop Transports are great for planetary assaults.
Cargo Transports can keep a fleet supplied with extra fighters, drones and more.
Since sat and mine launchers count as cargo, they work very well on a Transport hull.

As for resupply, most mods add the ability for Supply pods to count towards your cargo restriction on transport hulls. This means you can easily build a massive tanker to shuttle supplies from a depot to the front lines.

Once you get the tech, a single Quantum Reactor will be enough to keep your fleet fully supplied forever.

Re: newbie question
 

<font size="2" face="Verdana, Helvetica, sans-serif">Carrying spares. Take, for example, fighter combat. Fighters tend to break easily. If you have a carrier in your fleet, you can have a freighter full of spare fighters accompany it. You can then transfer fighters from the freighter to the carrier using the "Cargo Transfer" button whenever it starts to run low. Same goes for mines, satellites, drones, ad infinitum.

<font size="2" face="Verdana, Helvetica, sans-serif">One of my stock design types is what I call a "Fleet Tender". I usually build it on a Light Cruiser or Cruiser hull, with enough speed to keep up with the rest of the fleet, 2-3 Point Defense mounts, and the rest of the space being Supply Storage and Solar Collector panels. I've found that having several of these in your fleet greatly increases its "space legs". (They are also handy as 'Aegis' defense ships when facing a missile-happy enemy http://forum.shrapnelgames.com/images/icons/icon12.gif ).

Re: newbie question
 

<font size="2" face="Verdana, Helvetica, sans-serif">Troop transport are their main use.
I also have the habit to build specialized transports, like mine layers or satellite layers.
In the early game, the ship size "small transport" is quite usefull. It also costs too times less than a destroyer, which has the same tonnage.