Since Friday 6th is Twelfth Night or Epiphany, the International Edition will not be appearing, but will be back as normal on Monday, January 9th.
Basically, the usual transport and opening hours limitations apply as on all public holidays, with the majority of food stores (especially the smaller supermarkets) closed on Friday - the exceptions being the "usual suspects" like the Helsinki Central Railway Station underpass and the Kamppi Centre mall.
Banks, post offices, and Alko liquor stores will all be closed.
On the transport front, the simple answer is to encourage you to check out the websites of the service providers such as Helsinki Region Transport and Finnish Railways. Most services on Friday will be of the "Sunday timetables" variety, although late-night services into Saturday morning will be expanded.
On this occasion, a good many department stores and other speciality shops in Helsinki and environs WILL actually be open on Friday, owing to exceptional dispensations granted because of the volume of Russian tourists in town for the holidays.
For example, the Stockmann and Sokos department stores and the Ikea stores will be open pretty much as usual as though it were a Sunday, from 12-21 or 12-18. The same goes for the large shopping malls.
Things are, admittedly, more than a little confusing: shops are entitled to open, but by no means obligated to do so.
A fuller list of what is open and what is not (though this, too, is by no means comprehensive, given the strange circumstances) can be had in Finnish from the link below.
What is open and what is not on January 6th (in Finnish; bear in mind a good many department stores and other shops will actually be open under special dispensation)
Matkahuolto - long-distance buses and coaches
Finnish Railways, VR
Helsinki Region Transport, HSL