I've used them all plus some!
Often just the weight of the streamer is enough but from there it's your choice to get it down to the fish. I prefer a sink tip to using sinkers and also uesd to carry a 6, 12 and 18 inch sections of leadcore trolling line with loops on either end to add if needed. Now I've changed to using sinking line sections cut from a Rio fast sink shooting head/line.
An old gentleman, in Spokane was known for taking really nice trout from one of the many lakes there and he did nothing more than use a Rio 24′ Depth Charge Sink Tip Fly Line.
The 24′ Sink Tips are designed for big rivers where the fly must sink very deep and you have backcasting room to make this cast but as he found this is also a good lake fishing line for dredging the depths. He'd get that depth charge of a sinking line out as he let the wind carry his small boat across the lake. For rivers it's easier to sue a floating line and then have some sections of sinking line ready to loop on for sure as you want to be down near the bottom.
One nice trick is to just loop to loop your section of sinking line onto the fly line leader connection and let the loose end trail. It will hit bottom while your fly will ride slightly higher, especially if you put a corkie in front of the fly. (small Steelhead float)
As for leaders, you can go shorter in most cases using streamers. You can also go a bit heavier most generally. Mine likely average about 7 ft max and are tapered for ease of casting. Rio used to make a three foot or so leader that was treated to sink and I used that as a butt for the longest time. Now they have treated Versi-tip leaders that sink or you can get some additional sinking from using a leader made of FC.