How much of an influence/reference/relation Love Hina and Shakespeare was to Nisekoi?
I'm not that familiar with Nisekoi, but I don't find any of the similarities you mention very striking. 


Childhood marriage promises are very common in anime.
The first four things you mention that make Naru and Chitoge similar are all pretty standard tsundere traits. Tsundere as varied as Asuka Langley Soryu, Nagi Sanzenin, and Kirino Kousaka all share those traits with Naru and Chitoge. I acknowledge there is some visual similarity even beyond the hair antennae, but Chitoge also looks pretty similar to MM's Mio Isurugi, aside from the difference in build. Mio is even somewhat of a tsundere, to boot. And it's just a natural part of a story about a childhood marriage promise that the main heroine is probably the one who made the promise.
You acknowledge that all male shounen heroes are the same person.


All of these are standard clich&eacute;s for shounen romantic comedy. Some of them were popularized by Love Hina, and some have been around since Urusei Yatsura or even earlier. The reviews quoted here all call out Nisekoi for being full clich&eacute;s, bolstering my case that the similarities are just part of the genre. 

Also, in this interview, Nisekoi's creator, Naoshi Komi, says his biggest influence is not Love Hina, but One Piece.