Bhagavad Gita 3.13
यज्ञशिष्टाशिन: सन्तो मुच्यन्ते सर्वकिल्बिषै: |
भुञ्जते ते त्वघं पापा ये पचन्त्यात्मकारणात् ||
yajna-shishtashinah santo muchyante sarva-kilbishaih
bhunjate te tvagham papa ye pachantyatma-karanat
The spiritually-minded, who eat food that is first offered in sacrifice, are released from all kinds of sin.
Others, who cook food for their own ...
Hindus are not required to cover their heads while worshipping. However, scriptures maintain that the top knot (Shikha-the tuft of the hair at the top of one's head) has to be maintained. If this Shikha is not there then one is considered to be "naked from the top". So, the Shikha itself acts as a head-cover.
The necessary quote for the above point ...
Yes, most definitely. The most explicit and expressive hymn in praise of the Holy Cow is the hymn RV 6.28 of rishi Bharadvāja Bārhaspatya.
The full hymn with detailed notes and Sāyaṇācārya's commentary is here:
The hymn itself is below:
आ गावो अग्मन्नुत ...
This is because the same has been prescribed in our scriptures. Gautama Dharmasutra verses 6.1-6.3
(To salute) every day on meeting (by) an embrace of the feet,
And (particularly) on return from a journey,
(Is prescribed in the case) of parents, of their blood relations, of elder (brothers), of persons venerable on account, of their learning, and of the ...