Welcome to the Brethern JC.
1) Opinions vary widely on charcoal. It is worse than a religious discussion. I normally use Kingsford or Lazzuri (Cash & Carry) to get my big pit running. In my WSM I use Kingsford. Same with my old Brinkmann offset.
2) Wood... You can get wood chips & chunks just about any big box store. Remember, most people in this area think BBQing is a seasonal activity. Alder, cherry, apple are the main local woods. Hickory, mesquite, pecan all have to be imported. I tend to buy in larger quantities and splits.
3) Rule of thumb is 3 days on meats then freeze or toss. Vacuum sealing will help. How long the salmon keeps depends on several factors. Smoking is a preservation method. Also to keep in mind everything in smoker will taste like salmon afterwards unless you burn it out. One reason most people will either have a dedicated smoker for fish or just not smoke it.
Cold smoking: It is almost the prefect time of year for cold smoking meats - under 40F during the day. I use the AMAZEN smoker for cold smoking. In cold smoking I want smoke but I don't want to cook the product.
Bryan Lipscy - Dead Man BBQ - Washington State Spring BBQ Championship - April 26 & 27, 2014