Householder Michau, interested,
Is too much of good kamma an obstacle for enlightenment?
No, never, the path is pattern with good actions (kamma). There is no way to access and walk the path without kusala actions. If doing skilful without really having accessed the path it will lead to better states, better existences. If skillful on the path, it will lead to fruits, paths and liberation.
Even doing merits when actually leading the holy life, the Buddha told his monks not to fear such. One having gained stream would have another seven resistances. Would one spend them in possible lowest or highest birth?
So no. Good actions by body word and speech can never be an obstacle.
The more good kamma one has, the more likely one is to be reborn as a deva, and not a human, right?
Your current outwardly situation and kind of body is for the most a matter of past existences or great efforts in this life. Of course great situations are often an obstacle as one easy sees no reason why to put further effort into, thinking things are for sure. But where ever one might be for now, what done right here matters. That best or most worse situations are not determining ones success is good shown in the Darkness Sutta. That counts similar for Devas as well. Some are wise, have accumulated needed merits, some, even rich, waste such off. But once firm faith in the Tripple Gems there is less to fear to fall of again, yet right view need effort to adopt.
Later on, it says that devas actually aspire to be humans, in order to comprehend impermanence, suffering, and non-self.
My person doesn't thinks so, since if one is already aware of the Dhamma, why stepping back? And if not, enjoying lighter existences, who would desire for lower? Yet sure, most Devas have not gained right wisdom, might just be on "holiday" and could even fall into bad reams after the exhausting of their merits. As for what Devas wish each other, when one dies away, they actually ask for soon comeback:
"When a deva is about to pass away from the company of devas, five omens appear: his garlands wither, his clothes get soiled, sweat comes out of his armpits, a dullness descends on his body, he no longer delights in his own deva-seat. The devas, knowing from this that 'This deva-son is about to pass away,' encourage him with three sayings: 'Go from here, honorable sir, to a good destination. Having gone to a good destination, gain the gain that is good to gain. Having gained the gain that is good to gain, become well-established.'"
When this was said, a certain monk said to the Blessed One, "What, lord, is the devas' reckoning of going to a good destination? What is their reckoning of the gain that is good to gain? What is their reckoning of becoming well-established?"
"The human state, monks, is the devas' reckoning of going to a good destination. Having become a human being, acquiring conviction in the Dhamma-&-Vinaya taught by the Tathagata: this is the devas' reckoning of the gain that is good to gain. When that conviction is settled within one — rooted, established, & strong, not to be destroyed by any brahman or contemplative; deva, Mara, or Brahma; or anyone else in the world: this is the devas' reckoning of becoming well-established."
When a deva passes away
from the company of devas
through his life-span's ending,
three sounds sound forth
— the devas' encouragement.
'Go from here,
to a good destination,
with human beings.
On becoming a human being,
acquire a conviction
in True Dhamma.
That conviction of yours
in True Dhamma, well-taught,
should be settled,
as long as you live.
and whatever else is flawed;
having done with the body what's skillful,
and much that is skillful with speech,
having done what's skillful
with a heart without limit,
with no acquisitions,
then — having made much
of that basis of merit
through giving —
establish other mortals
in True Dhamma &
the holy life.'
With this sympathy, the devas —
when they know a deva is passing away —
'Come back, deva,
again & again.'
It's like coming here, this here is a fine-material realm as well. There are many who fall of back into normal human existences but less for them for practice sake, simply out of merits. And less are able to come back, once fallen off from a higher place. So who would not wish them to be able to come back and take a step even further now?
Others than the most think is, that the investment into meditaion without doing much merits aside that, without learing to develop right view, will cause them such Deva existances where they are caught for a long, not able to penetrate Dhamma and then, for the most, fall straight down into hell.
So the wise way is the same as in business. If working constant, virtuous and step by step by ones own effort, how ever less will stick with one, get not fast lost. There are many ways to make fast huge businesses but the ways and the debt cause them all to fall down as fast as the business has been grown. Not good and in-honest work will not bear long fruits.
May all those who have fallen of, being playful or corrupt, soon reappear where the Dhamma can be heard, read, and may those who have not been touched by such be informed by the Devas to join the merits.
(Note that this is not given for trade, exchange, stacks, entertainment and akusala deeds, but as a share of merits and continue such for release)