Hello!

I have few questions regarding to Groove A 52HPn routerboard:

1: What type of radiation pattern built-in antenna have (is it unidirecional)?
2: I want to connect this antenna to internet, and configure hotspot on it, to allow visiting only one site. Can i do it via Hotspot (does license Level 4 allows it?) or i have to configure firewall to redirect all requests to site I want to allow visiting?
3: what range can this antenna cover on open air?

Groove A 52HPn is just that a router with attachable antenna, if you see this product sold with antenna you have to query the seller for more information about antenna specs.

regarding the device itself - it can be used as hotspot device as license allows to have AP configured.
more specs you can check on routerboard.com

about License level limitations you can find on wiki.mikrotik.com (along with a lot of useful information about RouterOS capabilities and configuration possibilities)