No. Nokia 3310 do not have support for WhatsApp.
Nokia 3310 dimensions are 115.6 x 51 x 12.8 mm (W x H x D).
Yes, just like old Nokia 3310 - you will be able to replace both the covers and you can even create your custoised covers.
Yes, Nokia 3310 comes pre-loaded with Opera browser. But the speed will not be high as it works maximum on 2.5G network.
Yes, you can record videos.
There are a few things that do bring back the feeling of owning an original Nokia 3310, such as the classic Nokia ringtone, the physical buttons, the tiny body, and solid build quality.
You can buy other feature phones for less than this, and the new Nokia 3310 doesn't justify the extra outlay over the simple nostalgia card it's playing.