I am offering my answer based on the OP's reply to my query:
My query; You started your question in neutral tone without referring to any scripture - "It's said that desire for gains as intention for one undertakings, beyond simply that for liberation from suffering, is a huge hindrance, obstacle.". And, the 2 questions, you had put forward, are also general in nature. Are you expecting answers general in nature, based on SPIRITUAL concepts only, without referring to any scripture? or can be answered from other ways of thinking, say Hinduism?
answer; What ever householder @srimannarayanakv thinks that it would clarify and is truthfully, leads to release when put into practice.
So the OP is interested to know the answer from the householder's perspective. The questions are:
1) Now, what could, should one do, should avoid, that all kinds of such accumulations do not take place and do not endanger ones intention, aspiration, to bend from highest path and fruits, awakening?
2) Which role does maccharia (stinginess of five kinds and one primare cause) plays here, and if related, what kind of practice would work against such?
Rebirth in Buddhism refers to
its teaching that the actions of a person lead to a new existence after death, in endless cycles called saṃsāra. This cycle is considered to be dukkha, unsatisfactory and painful. The cycle stops only if liberation is achieved by insight and the extinguishing of desire. Rebirth is one of the foundational doctrines of Buddhism, along with Karma, nirvana and moksha.
https://en.wikipedia.org/wiki/Rebirth_(Buddhism)
The key issues are: The cycle stops only
(i) if liberation is achieved by insight, and
(ii) the extinguishing of desire.
I am quoting 2 slokas from Bhagavad Gita here, as the OP permitted me to do so.
ध्यायतो विषयान्पुंसः सङ्गस्तेषूपजायते।
सङ्गात् संजायते कामः कामात्क्रोधोऽभिजायते।।2.62।।
In a person, meditating on sense-objects, attachment or them is born in succession; from attachment springs passion; from passion arises wrath.
क्रोधाद्भवति संमोहः संमोहात्स्मृतिविभ्रमः।
स्मृतिभ्रंशाद् बुद्धिनाशो बुद्धिनाशात्प्रणश्यति।।2.63।।
From wrath delusion comes to be; from delusion is the loss of memory; from the loss of memory is the loss of capacity to decide; due to the loss of capacity to decide, he perishes outright.
https://www.gitasupersite.iitk.ac.in/srimad?etgb=1&etssa=1&choose=1&&language=dv&field_chapter_value=2&field_nsutra_value=63
Desire >> possessiveness >> anger (jealousy) >> delusion >> loss of memory >> loss of capacity to decide >> perishment
So every downfall starts with a desire and ends with perishment. This is the core area, which is common both to Hinduism and Buddhism.
Let us get back to rebirth as per Buddhism;;
The cycle stops only
(i) if liberation is achieved by insight, and
(ii) the extinguishing of desire.
Both actions are to be carried out parallelly either by a monk or by a householder, for getting liberation.
It should not be misunderstood that insight can be achieved (i) by attending to the discourses of scholars or (ii) by reading the preachings of the great Buddha or (iii) by doing meditation, duly following the techniques prescribed by masters of meditation.
No, it is not possible, as the desires, mentioned in the 2nd prerequisite will not allow one to get insight, unless they were brought under control.
Again, desires can never be satiated or cooled down by the enjoyment of objects. But as fire blazes forth the more when fed with butter and wood, so it grows the more when it feeds on objects of enjoyment.
If all the foods of the earth, all the precious metals, all animals, and all beautiful women were to pass into the possession of a man deluded by desire, they would fail to give him satisfaction.
The Indriyas or senses bring the man in contact with external objects and the desires are thereby created. But the senses are not all-in-all. If the mind co-operates with the Indriyas, then only is mischief wrought. Mind is more powerful than the Indriyas. Mind is the commander.
Reason is more powerful than the mind. Even if the mind brings a message into the mental factory by its association with the Indriyas, the pure reason can reject it altogether. Reason is more powerful than the mind. Behind reason is the Self, who is the director and witness of reason and who is superior to reason.
So practice to attain insight through meditation and checking the desires with reasoning should go parallelly, which slowly, but surely, brings the cycle of birth to end.