The only real detterrant for new players is the fact that their inventories are a one big fat zero when compared to veterans, and will remain so for years to come, unless they invest a lot of money.
I agree with this. The main deterrents for new players are 1) having to compete/being thrashed by superpowered alts, and 2) bugs and technical issues. That being said, there are some other problems with these proposals:
Remove trade base fee. Part of the fun of being a low level is to have to work for your stuff: struggling to get resources, the satisfaction of building stuff and getting new survivors. The trade cost is balanced so that you only want to trade for stuff you can't get yourself or desperately need. If you eliminate the trading cost, that fun is gone; plus I don't really want to go to the Trade channel to find 20 people begging for resources and basic stuff (begging is bad enough even with the cost).
If you just reduce the trading cost instead by eliminating the 10-fuel fee those problems are not as bad (though still increase), but the new players won't really see it as "Yay! only 5 fuel to trade", but as "I still have to pay fuel to trade". This, coupled with the fact that it's not even one of the major turnoffs from the game, would mean that it won't attract enough new players to justify the unbalance the rest of us would experience.
Reduce return times. The new players are the least affected by return times, since they start small at 5 minutes. If you reduce the time by 50% the DMU sales would fall, since getting a UCS50% is not hard at all for most of us.
One thing that could be improved, however, is the return time increase over level; right now, missions with level 27 have the same return time as a level 60 mission. I would prefer that those times were revised to give the full 4 hours to players lvl 40-45 and up instead of 50% off for all. That way it wouldn't be as hard for lower levels while still keeping things balanced for the rest of us.