In the 2015 Space Marine Codex there are 10 different formations that you can add in to your army list. No you will not be able to add all the formations in to each game, the formations will cost more points than the game limit will allow. If you play a super massive Apocalypse game then you may be able to, but that is what Apocalypse games are all about!
Are Space Marine Formations worth it?
Formations usually add some special rules that can give you a gaming advantage. The cost of this is that the formations normally have a formation structure and often other restrictions too.
So is it worth jigging your army list around to accommodate formations? I believe that if the changes are in line with your game plan, then you may find that slipping the formations in to the army list. However the special rules usually do not give such a big advantage to warrant making major game plan change
Space Marine Battle Demi-Company Tactics
The Space Marine Demi-Company is a fairly strict formation of mainly troop based designed to be a core army. The advantage of this formation is that it is easier to claim contested objectives. With the Maelstrom of War scenarios taking objectives is a major part of the missions.
Space Marine Anti-Air Defence Force Tactics
With this formation you need to know that you will be needing a major amount of anti aircraft support, or anti Monstrous Flying Creature support.