Hra & interest on home loan

Yes. IF he can convince that he residing in a rented premises.  (advise him to pay the rent through bank)

yes u can claim both H.R.A allowance and Repayment of housing loan under 80C.as bujjulu told it would better if u make payment through cheque and as u mention at last both property occupied by his parents and property for which he paid rent are in the same city.it is relevant just for showing Income from House property as NIL. because to show income from house property as NIL,u should not be in the same city where ur own house property is located even though u paid rent for another property.but in case of H.R.A,u just need to prove that u are not staying in ur own property and u are paying rent for where u r staying.