Diet wise, Bengals need no special diet at all. They are just domestic cats like any other cat breed.
Lots on here feed their cats, Bengal or other breeds, a raw diet so it is as close to how cats would eat in the wild. Failing that, a high protein wet food.
Kittens are best being rehomed at 12/13 weeks as they get all the socialisation from mom and siblings plus are fully vaccinated. I struggle to understand how someone can be struggling financially to keep a 13 week old kitten when they can't have had him that long
Weird and slightly irresponsible of them... their loss is your gain though
He won't be full bengal if his 2nd home came at 13 weeks old i bet. Even bengal crosses sell for £100's usually so, unless you paid a fair bit for him, i would imagine he isn't a bengal cross (one that somebody purposefully bred). However, any moggie cat by definition is a mixed breed so he could have any genes, it's entirely possible he has some bengal somewhere.
Stick around