The Manu Smriti simply says to change the thread when its damaged.
Manu Smriti 2.64. His girdle, the skin (which serves as his upper
garment), his staff, his sacrificial thread, (and) his water-pot he
must throw into water, when they have been damaged, and take others,
reciting sacred formulas.
Some further conditions when the sacred thread ...
The questions are:
Were chaturashram (4 stages of life) applicable for all the 4 castes (Brahmin, Vaishya, Kshatriya, Shudra)?
Did lower castes really get the chance to observe bramhacharya, i.e. to be educated?
Yes, it is applicable to the people of all varnas.
The four ashramas are: Brahmacharya (student), Grihastha (householder), Vanaprastha (retired)...
There are several types of meditations to choose from like stillness meditation, mindefullness meditation,Shambhavi meditation and SoHum meditation.
So far, the easy to practice and widely recommended one is sohum. But the thing about meditation is, try several methods till you find the toughest one to practise and stick to it. You will definitely reap ...
Was Chatur-ashram applicable for all the different castes?
No, Shudras are considered life-long grihasthas.
Shudras only belong in one Ashrama as per Gautama Smriti:
Live with his wife (only)
'Another commentator explains the Sûtra to mean that he shall live with his wife only, and never enter another order (i.e. never become a student, hermit, or ascetic)...