bro,
as i said there are four states in south india.each have their own distinct features from other states.and people generally think they are all tamils.
tamil nadu and sri lanka belong to same ethnic group,this people generally look little dark compare to other three 3 states may be myth or real i heard due to heat and high temperature at bottom of india close to equatar
still tamils are hugely mix up,iyer ans iyengar community of tamil nadu are extrmely fair some of the best looking actress in bollywood like hema malini,rekha,vidya balan,waheeda rehman, come from tamil nadu .from my state we had sri devi,jayaprada,tabu,dia mirza e.t.c no males though they show them as some jokers or bad villain with big moustache with extremely dark in colour.
trust me 60-65 percent of indians look same in colour brown,20-25(mostly lower caste and mainly from south india ) percent would be dark,reaming 20-25 percent as fair(for all ethinic groups,majority from north india) features may be defferent based on region
muslims in south are mixed with local converted ones,only that they don’t follow caste system,i can see lot of fair skin ladies marrying with local kind of dark or brown look,i think they follow islam in true sense without giving importance to race and colour.
even we have miss match in my community too,this women mostly marry for security though 
from what i saw 70 percent have beard and women wear burqa without covering their face though,this is what most of the impression indians get about pakistan like everyone grows beard and wears burqa and looks like afghanistan (thanks to media for this part)
there is no such thing of hindu nationalists unlike taliban or some mullah this guys don’t give **** about religion.
you can term this guys similar to mqm they use hindu card politically to get votes,heck most of them are atheists who just fakes,in south we never had any BJPuntil recently in karnataka thats more to do with people in bjp with huge community vote bank and ant government senitiment.
to be honest personally i prefer bjp rule and modi has PM.this is going well with urban population,after all the religious clash amount of development gujarat is just incredible.being one of the smallest in terms of area and populationnominal GDP of gujarat is close to 100 billion$$ .he can do brilliant job given the pm post.if not it won’t change anything from our present scams,our current pm is one of the best with no real power in internal political matters :\
coming to ur question yes there is favorable treatment,but it’s more to do with backward caste,scheduled caste,scheduled tribe then religion it’s really unfair,they should remove caste system and aid should based on poverty line,but politicians won’t do it,they need caste votes
let me give you one example:
when i gave medical entrance exam out of 80000 students in my home state highest during my batch(30k normal number),me being OC(forward caste) should get rank within 600-650 for mbbs,1-2k for veterinary,2-3k dentist.
if ur from sc/st/bc u can get mbbs seat even if u get 10k rank,suppose if one of guy in 650 leaves seat gets seat some other medical exam like AIIMS(ALL INDIA) that vacant seat would be given to some 9k rank guy from backward caste then 651 rank from oc doesn’t matter if that oc guy is poor and this bc guy been rich,i had to end up with biotech engineering with 5lakh donation yearly 1lakh fees.
yes there is conversion from hindu to muslim,but you have to take into account amount of population during 1947 inda had around 100-200 million compare to 1.2 billion today
compare to hindus you have big families in muslim community which is practised even today