Yes you can take but in half quantity of winter's Take steam twice a day Use shadbindu tail in each nostrils Consult on app for further treatment

Why not . But there is so many Ayurvedic medicines for allergic rhinitis. You may consult any Ayurvedic doctor

Yes, chyawanprash is safe and can be taken in summer if it's suitable for your bodytype. It contains few herbs like Black Pepper, Pippali, Ginger etc which are Hot in Potency and can cause Heat in the body if Particularly you have a PITTA prakruti. Just be vigilant, incase you feel any sort of Heat or Burning sensation anywhere in the body/stools/urine, then better avoid it.

Consult any ayurveda physician you wl get  benefit definitely avoid self medication Better  you need to take vaman. .you will be free from disease. Consult 

Better avoid it in summer

Yes you can. But also do Bhramri Pranayam, will be helpful for rhinitis.

Yes sure no issues

Yes

Find out root cause of your problem by ayurved way diagnosis Correct it by ayurved way medicine diet and lifestyle corrections Finding out root cause and its cure is very important for improvement or permanent cure naturally Correct diagnosis by ayurved way is very important main factor in treatment Take any ayurved medicine after proper ayurved way diagnosis only for avoiding bad effects of intake Take online consultation directly for accurate diagnosis and treatment diet chart home remedies