What are the symptoms of high triglycerides?

Depends . If high enough(greater than 500) can cause pancreatitis and abdominal pain and nausea and vomiting would be present if its related to poorly controlled diabetes, your sympyoms may be more related to the diabetes. Excessive thirst, frequent urination, change in vision, etc. Otherwise if high but not excessive no symptoms would be noted.
Depends on the level. Patients with very high triglycerides (tg's) >500 are at risk for pancreatitis, which usually presents with abdominal pain , fever, nausea and vomiting. Usually not seen until the tg's are greater than 1000-2000. Very high tg's, can also cause fatty skin lesions called eruptive xanthoma, often seen first by the dermatologist. Unfortunately, in most cases moderately elevated tg's have no symptoms.