No. You cannot download whatsapp in Nokia 3310.
Yes, Nokia 3310 does have a speaker available just beside the rear camera. Nokia 3310 does have conference call option.
No. You can not install WhatsApp on it.
Yes, you can create contact groups in Nokia 3310.
No. Nokia 3310 do not support 4G and VoLTE.
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.