Ok...
In response to your first question...
Yes, if you cut the shoulder in half, in a perfect world you'll cut your cook time in half
As far as how much to smoke...
I've always been of the opinion that a full smoker makes more sense...it doesn't take any longer to smoke and smoked pulled pork freezes and reheats very well and you'll spend far less time and use far less charcoal...a full smoker is a happy smoker.
As far as fuel consumption goes
That depends on your lighting technique. If you use a propane torch to light your charcoal in the smoker then it'll be close.
I can get over 10 hours on one full basket but usually not more than 12 at temps of around 250° F
If you light your charcoal using a chimney style
charcoal starter and the minion method of pouring alot of unlit coals in your smoker and adding the lit coals to the unlit I usually get about 8 hours of burn time.
So to use the side light technique with a torch...
First fill your bowl as full as you can get it next add the center barrel section (just like you were getting ready to smoke)
Make sure one of the holes in your charcoal ring is aligned with one of the side/bottom vents so you can stick a lit torch through the vent hole and reach the unlit charcoal.
Wrap your water pan in a couple layers of foil...it'll make clean up way easier (you'll see)
If your using water in the water pan position the EMPTY PAN in the smoker and add water by pouring it into the pan from a pitcher or gallon jug...it's WAY TO EASY to spill a pan of water on your charcoal trying to put a filled pan in the smoker.
Most of us don't use water in the pan...the water serves no purpose other than to act as a heat sink...we use sand, lava rock, gravel...I've even just used a few baseball sized stones
The purpose is to have something to get hot and help hold and regulate the heat...
Once this is done put your thermometer in the smoker and close the lid.
Open ALL the vents FULLY (top and bottom)
Light your torch and stick it in the aligned vent hole and light the charcoal...I usually light it in two places through two different bottom vents.
It will take about 5-7 minutes (maybe 10) in each location you light to get a 6-8 of the coals well lit.
Smoke wood...I use chunks and add them through the door of the smoker after it's lit.
I add about 4 fist size chunks one on each location I lit coals (usually two places) and the other two pieces on unlit coals as far apart as I can get them...these will light as the coal does and provide smoke for a longer period of time...I add a chunk as needed to have consistent light smoke for 4-5 hours...sometimes the original 4 are enough, sometimes it requires adding 1-3 more depending on the size of your chunks and how windy it is (longevity of the chunks depends n air flow; air flow is effected by wind)
Once your coals are lit and wood is added monitor your temp and when it reaches about 10-15 degrees HOTTER than your target temp pop the lid and add your meat...one piece per shelf and put the lid back on...
After about 15 minutes the temp should start to recover...when it does close your bottom vents about half way leaving the top wide or nearly wide open.
You'll need to adjust your bottom vents to adjust temps.
Wide open will raise the temp, more closed will lower temps.
On my 18" I find my bottom vents are usually 3/4 closed and top about 3/4 open to maintain 230-250° temps.
Don't chase the temperature trying to get it exactly right. The recommended 220-250° for low and slow are guideline approximations...260-275 even 300° spikes don't hurt ANYTHING AT ALL just as a short drops to 200 won't. Always wait at least 15 minutes after a vent adjustment before making another.
If you need to add more charcoal, add it UNLIT through the access door before all your origional coals are out...those remaining coals will light the fresh charcoal.
I usually add about 10 -15 unlit briquettes one at a time using my long BBQ tongs when about 3/4 of my origional fuel has burned up...it is common for the temp to rise, some times a lot when the door is open...don't worry and don't adjust your vents...close the door when your done adding charcoal and see where it settles in...usually the bottom vents need to be opened slightly for 15-20 minutes when unlit charcoal is added for it to get going.
Now after all that long winded stuff...this is what works for me...your results will differ but this gives you an idea anyway...
FYI I've done about 200 pounds of pork butts and shoulders this summer alone so it is with fair confidence I share this info with you.
Hope this helps you...
Good luck and have fun...
Oh...white smoke vs thin blue...
Using this technique you won't get much if any objectionable smoke...sometimes it's hard to tell white from blue...
What you want is light "wispy" smoke...
You don't want billowing thick clouds of smoke...you'll notice thicker smoke at the start and maybe if you open the access door and let in a burst of fresh air but as long as it's brief (less than 3 minutes or so) you won't have any issue.
Hope all this bla bla bla helps
Walt.
