help with shot placement and fly depth

Did  a search and now I thought I would ask.   What are the distances for shot placement from the fly for different water conditions/ speeds and flies.   I have been placing about 18 inches up and using as little as possible to get it down.  I have read to place shot smallest to largest from fly to flyline and sometimes spread the shot out a bit.  I have also read to use a tag on a swivel too.    How bout one on fly depth too.  Egg patterns should be on bottom right?   How bout, buggers and streamers. Bottom, just off, middle    

Just learning, thanks in advance.  I am going to bed and will read replies tomorrow.   I also want you guys to know that this forum in particular has gotten me started on serious fly fishing and thanks so much for all the help.
Clint

All those flies can be anywhere but as a general rule real eggs are in the bottom 1/4 of the water column , so an egg fly should be also.
Also eggs are usually more effective dead drifted not swung.

Streamers can be fished anywhere in the column.A lot depends on the water temp and speed.
The warmer the water (this time of year is perfect)the further a fish will move either horizonaly or vertically to chase one down.
Buggers?
See above on streamers. I will say that I have more success nearer the bottom. Doesn't have to be on the bottom but near it has been best for me.

Weight?
1-2 fett from fly.
Smoother shallower water you can string out the weight (it will fish the leader more like a sink tip).
Verying the size has always caused the cast to collapse on me sometimes leaving knots a sailor couldn't tie.
Heavier water the weight should be closer to the fly and bunched or a larger shot should be used.
All the weight in 1 place speeds the sinking and in heavier water and small short pockets getting down in front of the fish that may be holding near the head is critical.