Gastric Ulcers are open sores or lesions in the gastric mucosa. Causes and treatments are the same as gastritis. Untreated ulcers may lead to perforation or bleeding.
Bleeding from ulcers can be a serious, potentially life threatening condition. 
Cauterization of bleeding can be accomplished safely and effectively through EGD and use of bicap, heater probe, or laser. This cauterization is often sufficient to control bleeding and prevent patient from undergoing surgery. If cauterization is unsuccessful, the sight of bleeding is injected to induce vascular constriction.
Helicobacter pylori is as a bacteria which has been associated with chronic gastritis. 
Treatment includes the use of antibiotics as well as H2 Blockers of proton pump. Ulcer may be present since the bacteria weakens the stomach lining and damage by acid can occur. This bacteria can be detected by biopsy taken during EGD, and recently as a blood test is also available to detect the presence of H-pylori.
Surgical intervention for the treatment of ulcer disorders is sometimes necessary to remove diseased areas and prevent reoccurrence of bleeding and persistent symptoms for non healing ulceration.
Vagotomy is simply cutting of the vagus nerve in an attempt to decrease stimulation of parietal cells and decrease impulses to muscles of the stomach, intestine and gallbladder. P
arietel cells are responsible for the secretion of HCL acid and are found in the gastric mucosa.
This procedure may impair gastric emptying and therefore is usually performed along with a Pyloroplasty. Pyloroplasty is enlargement of the pylorus to allow adequate emptying of the stomach. Gastrectomy is removal of the stomach or part of the stomach. The procedures are Billroth I or Billroth II.
Billroth I is removal of the gastric antrum with reanastamosis of the stomach remnant to the proximal duodenum. Billroth II is removal of the antrum with reanastomosis of the stomach remnant to a loop of the proximal jejunum, food bypasses a large portion of the proximal intestine resulting in suboptimal stimulation of bile and pancreatic secretions.
Source: Endoscopy: An Insiders Look
by Krista M. Stayton