@Mark M Can you post alink to the smoker you have as it'll help with answering your questions. Is it the Callow/ Cook4All one?
A few quick answers
1) I normally find about 2kg of heat beads will give me a smoking time of about 7-8 hours, obviously it depends on the temperature you're smoking at and your bbq of course.
2) Depending on the smoker, you'll either want to use the
a) minion method, whereby you put most of the briquette into the charcoal basket of the smoker leaving a dip in the middle. Then you light up to about a dozen in a chimney. When they're nicely alight and covered in grey ash. put them in the dip in the charcoal basket and add your wood chips around on the rest of the briquettes.
b) snake method whereby most of the coals are arranged in rows around about a third of the edge of the smoker, something like 2 rows wide by 2 high. light about 6- 8 coals in the chimney and add them at one end of the snake, with wood chips scattered along the snake.
3) Shouldn't need to as both the methods above slowly burn through the coals and hence slowly through the wood chips but if you do need to it's not a problem.
4) if you want to use the water pan, first line it with foil (trust me this is worth doing!!) then stick about an inch or so of boiling water into the pan.
5) you want the grill probe on the same level as the meat, no point knowing what the temperature is else where in the smoker as it could be quite different from top to bottom!
6) a bit of research on various forums will give you an idea of how long things take but really the whole point is that you're cooking to temperature..
7) shouldn't need to using either method mentioned above, unless you're smoking for a very long time
8) the cold weather won't have too much of an impact on your smoking really, it might take a bit longer to get to temperature as it'll be heating the metal of the smoker but once you're there you'll be fine.
A great forum for BBQ info:
http://www.woodsmokeforum.uk/