Does it come assembled?
Some assembly is required.
Do they come in gas and electric?
All ventless cooking units are all electric.
Are ventless ranges more effective?
Ventless ranges are as effective as traditional ranges. The advantage of ventless equipment is the flexibility in where you put your equipment. They also eliminate the need for permanent alterations to buildings.
Do I need a hood?
All ventless cooking units are completely self contained. Ventless hoods are also available for traditional cooking equipment. It is always a good idea to double check local codes to be sure equipment meets those standards.