Can Zyrtec be given to help cure running nose and nasal congestion in a kid?

Hello doctor,

My 3-year-old son weighing 40 pounds seems to develop running nose along with nasal congestion today afternoon. He also seems to have some amount of breathing difficulty today while sleeping, although he does not have any background in asthma.

I have some questions:

1. I have given him Zyrtec (Cetirizine) syrup today late evening, which probably makes him feel a little better. Also, I am planning to give the same twice daily for tomorrow and day after unless something else comes up. Is this a correct medicine?
2. We have a nasoclear nasal spray, however, he is extremely reluctant in taking it. Is there anything else we could do for his nasal congestion? Also, usually he develops some amount of throat pain the next day. Is something like one spoon of 'Ibugesic Plus' or 'Calpol 250' fine for that?
3. Is it fine to give him curd, fruit juice (orange, pomegranate) or fruits (apple, banana) during his sickness? Please advise if any of the above is not recommended.
4. Since the last few days, he used to sleep a little in the late afternoon. He wakes up late and as a result, takes fruit juice (orange) and fruits like banana little late in the evening. Is this a probable cause of sickness?
5. He has taken his flu vaccine appointment in two days. Given he is sick and in case it continues for a couple of days, will it be appropriate to give the vaccine?
6. What is the preferred time for the flu vaccine? Should we give flu vaccine now or wait for some more time?

Hello doctor,

My 11-month-old daughter. She currently takes three meals and one snack, in addition, to breastfeed. Please advise if anything needs to be rectified. She has:

1. Tinned baby foods.
2. Rice with dal and vegetables and fish and chicken.
3. Fruits like apple, banana, orange, and raisins.
4. Chapati along with fish.