Before I get into this I'm going to go ahead and "solve" (part of) your second problem for you.
Use the initial miner to build asteroid mines. If time/the map permits, build a second one (and possibly third, but let's not get ahead of ourselves). An extra 12-15 production on your homeworld is a godsend. In some instances it can be worthwhile to convert the starting colony ship to a miner as well, but most of the time you're better off getting a 125% boost to empire-wide research (24+14+16 from hyperion matrix=54 as opposed to 24) by colonizing the first planet you see. Taking the +50% military production bonus is invaluable, and it only costs 4 points (whereas social +50% costs 5-that's always bothered me).
Stock Thalans can be a colony rushing beast with this, due to their innate +33 social/military production. Even so, it's probably better to go custom and tack on +1/2 speed-which brings us to the other issue of the Thalan tree not meshing very well with their SA.
Granted, without access to research structures, it's still difficult, in the circumstances you've outlined, but it's not as difficult.
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I've got two issues to present-both of which can be "solved" via tech trading, but as I understand it that's not a valid solution in your book-nor is it in mine.
Invasion:
-Iconians are missing Tidal Disruption (TA preferred tactic when you don't have the techs anyway).
-Thalans are missing Core Detonation, Tidal Disruption, and Mass Drivers. Combined with their low(er) soldiering from techs and their lower population due to no farms in their tree, this can be fairly devastating.
-Yor are missing Core Detonation and Tidal Disruption.
Morale:
Everyone but Arceans, Terrans, minor races.
You wind up missing the following:
+15 morale (Xeno Entertainment)
+15 morale (Extreme Entertainment, Zero G Sports Arenas, Virtual Reality Centers)
+15 morale (Ultra Spices - Extreme Entertainment)
+12 morale (Virtual Reality Modules - Virtual Reality Centers)
For a total loss of 57 morale (about a starbase and a half, fully upgraded).
-Altarians/Drath get 20 from techs (loss of 37), while their maximal morale improvement is 18%.
-Drengin/Korath get 15 from techs (loss of 42), while their maximal morale improvement is 25%.
-Iconians get no bonuses from techs (loss of 57), and are stuck with a 25% morale improvement all game long.
-Korx get no bonuses from techs (loss of 57), and are in an even worse position as they can only build one of their 25% morale improvements per planet.
-Krynn get no bonuses from techs (loss of 57), and are limited to two one-per-planet morale improvements for a total of 50% (20+30). For the stock Krynn, this is hardly an issue, but it becomes noticeable when playing a custom with their tree.
-Thalans get 25 from techs (loss of 32), and have a maximal morale improvement of 25%. However, theirs is dirt cheap, and they don't have farms in their tree, so they don't need it as badly.
-Torians get 5 from techs (loss of 52), but have a maximal morale improvement of 50%.
-Yor get no bonuses from techs (loss of 57), their maximal morale improvement is 20% and is linked to a 3mt/wk farm, and they have a separate 20% one-per-planet improvement.
You can consider the above to be a loss of 30 if you treat trade goods as buyable, which works so long as you have at least one AI in your game who will 1) have it in their tree 2) get that far and 3) build it. Don't rely on the minor races for that.
If you have tech trading on and can manage to get the techs, you have nothing to worry about, but it's something to keep in mind.
The best solution to this issue is to adopt a one-farm-per-planet rule (whereas DA with its standard morale bonuses and structures could support two).
[Edited. Thanks.]