1. No, engines would only allow you to setup the trade route sooner. It will not do anything once the trade route is established. A trade route freighter always travels 1 parsec per turn. Always.

2. I don't know. Maybe it measures how much research you actually do. I don't consider that report very important anyways. You can be technology inferior but still win.

3. From what I understand, the length of the trade route and the population of the target world plays a factor. But normally I ignore that. I use freighters for diplomatic purposes. Having an active trade route with a civ improves relations, so I favor routes that makes friends not money. I target their homeworld since they should have a good economy there.

4. Not sure. I'm not an expert in trade routes. I don't think it would hurt to trade the techs. I would be more worried about trading weapons techs than trade techs. If they consider it valuable, then maybe you can trade it for something valuable. For the record, they might end up making trade routes with other civs instead of you.

Hello Donnerjack,

to add to DivineWrath's reply on 1: depending on your military production output engines can even delay your freighter income - assuming you spend very little on military production overall or that planet where your freighters are being built simply hasn't many factories then adding additional engines could delay the release for several turns. As such, you should recheck that and compare it with the distance your freighters have to travel. Ususally you need freighter in the early stages of the game, a good engine there is "Ion Drive" because it costs less per speed than other engines.

However, there is a better way for this: *Trade* for other empires Freighters, or Scouts (and turn these into Freighters through upgrade, needs some basic & enhanced miniaturization for it). The advantage is that these shops are usually very far away and near potential planets that make a good target to send the freighter in. You'll need decent range so that the upgrade doesn't take too long (build Starbase for this)

2. Trading research (or better: technologies) doesn't add to your research graph or meter. Only your research points (flasks) generated by your planets/labs does. 

3. I found that the distance between the 2 planets is the most important factor. On the population/economy of these planet's I'm sure... I made some tests in game but I saw now correlation... However what's further important is that the planet isn't in immediate danger of being conquered or culture-flipped, because your route will cease with it. Additionally, your freighter should traverse safe grounds, because it's of no use if your minifreighters always return home after half of the route, because that will cut down their income as well.

4. You can even trade it to hostile races because it might lead them to send freighters to you as well, possibly delaying a declaration of war... however, make sure that you build the wonders beforeahead, IMO the Galactic Bazaar is overpowered and therefore a MUST!