Achievements should not be added "just because everyone else has them". The game will eventually (hopefully) have relatively slow progression towards new ships and later towards a larger fleet and even, a larger empire. Having stats will have more or less the same effect as achievements, as suggested.
If, however, achievements is something that the community or the developer wants to include, they should be done well. After reading the blog I get a feeling that we are in good hands as Alex has clearly given this some thought and understands many of the pitfalls and behavior that achievements can endorse.
A relatively good example for use of achievements was the first mass effect. The achievements unlocked bonuses for future playthroughs and unlocking the achievements actually felt like an achievement. Unfortunately that did not catch on and the standard achievements are usually just virtual bragging rights.
What I would rather see in a game like Starfarer is something similar to ME. You could "receive medals" or unlock traits by performing certain tasks in addition to the level progression. This could add something to the game if the goals are selected properly. To give some concrete examples of what I have in mind it could be something like:
-getting one million (or any other amount) profit through trading would give you a permanent bonus for prices. This could be a multistepped "achievement" with increasing bonus. Or maybe you would get a bonus to available cargo space.
-fighting 100 battles with a fleet with at least 10 ships could give you a permanent bonus to fleet size
-training 100 crew from green to elite would give you the title "mentor" (or something) and improve the rate of learning for your crew. Again, possibility for multiple levels.
and so on...
Of course these depend on what the developers have in mind for the leveling system so that the achievement/trait-system would not be completely redundant.
EDIT: Removed a question as I found the answer elsewhere