Duration depends on your targets, for example you might want to get to 200 pounds so you keep bulkiing until then OR like most people bulk during the winter say until March/April then start cutting up for the summer.
Best supplemenss when bulking - depending on your bodytype if you have problems putting on weight than go for a weight gainer like NLarge2 otherwise get some decent whey protein powder like EAS or Optimum. Creatine is good so is a multi-vitamin and ZMA is also worthwhile if you can afford it. Best supplement is food though- chicken, tuna, eggs, milk, cheese etc should build the bulk of your diet.
For cutting cycle keep the same routine with weights maybe reduce volume a touch- dont switch to high reps or youll lose more mass and strength than necesarry. Add 3-4 40 min cardio sessions first thing in the morning or after your weights if you cant find the time( make sure you reduce volume with weights in this case). Best supplements would be whey protein powder again , multi-vitamin ,Glutamine and a good fat burner like Xenadrine or Animal cuts.
Remeber to eat 18-22 (if you put on weight easily x 18 otherwise x 22)x your bodyweight when bulking split over 5-6 meals and when cutting gardually reduce to 10 x your bodyweight split over 5-6 meals.