took for himself the title of Vikramaditya, which was pretty much equivalent to that of emperor AFAIK
Just taking a title means nothing. He at the head of an army proclaimed himself Vikramaditya (meaning Valour like Sun rather than emperor), which we don't know how serious the claim was, considering that the claim could have been just a title as a victor and nothing more and given the composition of his forces with many afghans and other muslims, declaring independence could have monumentally backfired. He till his death never formally broke with his sovereign and declared a proper independence, so I would take an independent claim with a grain of salt.
How different would this "Hemuan empire" be, compared to the one established by the Mughals IOTL?
His mere existence doesn't mean anything, the most likely scenario, which is making a big assumption that the would take over the Sur Empire is that we see a steady continuation of the policies of the Sur empire as had been seen in the reign of Sher Shah Suri. He was a servant of that empire and spent a great deal of his career in that empire's service, so he would most likely continue with such policies, a secular empire with a focus on trade and administrative efficiency, lessons probably would have been learned from the unravelling of the Sur Empire after the death of Sher Shah Suri. The trade route projects would have been completed earlier and we would have seen a growth in Indian Industrial trade and many of Akbar's officials like Raja Birbal and Man Singh would have probably joined his court and most prominently Raja Todar Mal would have continued his revenue reforms.
Hemu empire will give rise of local noble at the place of mansab.
there will be more centralised control on the government then akbar
Well it seems contradictory. A local noble in charge means decentralization, mansabdari system before corruption came in was actually a step forward towards centralisation as persons not locals are appointed in a particular area, the only plausible way to go forward is to have something like Mahalwari System.
There would be a good chance
of Vijayanagar being victorious at Talikota.
And your reasoning for that being?
Hemu's win would mean the break up of larger polities in the northern part of the country, most of which would be under Hindu rule, Hemu would be unable to establish any form of kingdom let alone an empire and even he did, the empire would collapse soon after, resulting in the Balkanization of political entities in the North.
If he kicks out the Mughals and breaks the back of the Sur Empire and most plausibly struggles then I see a similar balkanization with plenty of Hindu and Muslim kingdoms.
Bengal would never emerge as the economic powerhouse which it was in the 1700s as Bengal was basically a product of Mughal political and economic investment and this would never happen in this timeline and Bengal would remain a mix of Hindu and traditional religions much like it's neighbors Assam was at the time
Bengal was already quite a wealthy region due to overseas trade in relation to the other parts of India. Without Mughals the economic situation doesn't grow to the mammoth proportions to the levels OTL but is still quite large, projects like Sher Shah's Grand Trunk Road only increases the hinterland of Bengal and encourages growth. I guess you didn't know that Bengal was already majority Muslim by this point in time, with the shift in the main distributary of the Ganga from the Hugli to the Padma settlement in the previously densely forested east increased and during that time the Muslim Rule in Bengal was established and settlement was like a frontier society where a village is created by burning out a clearing and establishing a mosque and a few huts. Is encouraged massive settlement and conversion, creating a region with Muslim majority thousand+ kms from the next Muslim majority region. The caste system in Bengal, also comprising a system known as the kulin system was a social evil that made other social evils of India look tame didn't help matters either. The Sena dynasty in its persecution of Buddhism had come up with that scheme and the surviving Buddhists found the invading Muslims to be liberators and were the bulk of the converts.
Hinduism IMO would reform itself as it's adherents in various parts of the region would once again gain political power and patronage to various local variety of Hindu centers of learning and various new cults and sects would emerge in different region eventually would culminate in a particular school of thought or sect gaining political dominance, probably Sikhism emerges as the majority religion in Punjab and would probably remain as a part of wider Hindu thought and may or may not emerge as a independent religion and parts of Islam would enter Hindu religion as much as local Hindu sects and cults influencing Islam leading to different Hindu sects similar to that of Sikhism emerging in different parts of the subcontinent.
The Bhakti movement was slowly losing steam and if it continued a lot many reforms could have been achieved. The lack of growth of Islam in Punjab surely leads to more Sikhism or does it? The significantly altered dynamics may lead it to go either way.
