Does Samsung S7 smartphone support OTG?

Obviously, the Samsung Galaxy S7 does support USB OTG functionality. You can connect your external hard drives to the device and view the files stored on them. Make sure the hard drive you are using has the right file format supported by the phone.
Also please note that you will need to buy the OTG cable as a separate accessory.

Yes, the new Samsung Galaxy S7 supports USB OTG functionality. But one has to buy the OTG cable separately as an external accessory, as it won't be available within the box. Now you can connect any external hard drive with the device and it would be easy to view the files that you have stored in those drives. But you have to check out whether the hard drive that you are going to connect has the right file format and has its support in your phone.

Samsung Galaxy S7 supports MicroUSB 2.0. And it does support the OTG functionality. OTG feature allows you to use the device to be used as data transfer as well as for charging the device.

As for your second question, It has following connectivity options such as - bluetooth, Wifi, MicroUSB and hotspot. And it obviously has support for GSM, HSDPA and LTE. This also includes GPS feature too. It comes with two different models single SIM and Dual SIM so the connectivity options change respectively. Being a high priced mobile both the models (single and dual SIM) have NFC supported as connectivity option too.