There are no instrument approaches due to terrain at EIS. All approaches are VFR only. VFR approaches can be conducted day or night. EIS is normally closed from 2100-0700 however the hours can be extended with prior permission. The airport has standard lighting for night operations. There is also a visual glide path indication.
The big difference between a airline and corporate operation is the airline is on a fixed schedule. Larger airlines are very reluctant to serve a airport without a instrument approach because any weather can cause expensive diverts that snowball. Crews and aircraft end up out of position. Those diverts can quickly eat up all your profits.
Most approaches in the US are somewhat of a hybrid approach for both corporate and airlines. You are on a IFR flight plan and use instrument rules. If the weather is VFR controllers will give you vectors to the airport until you report it in sight. They clear you for a visual approach and kick you loose at that point. If the field is below VFR mins then they will clear you for a instrument approach however this reduces the arrival and departure rates for airports so they stick with visuals as often as possible..
Airports in regard to your qualification question for corporate or private operations do not require special quals however the better operations will have a system like the airlines where airports considered difficult will have some additional requirements. Usually this is reading a briefing guide. Airline operations require a special airport qual program. Depending on how difficult the airport is it may be simply reading a briefing guide all the way up to a dedicated simulator ride followed by a first entry with a check pilot. EIS would certainly be a special airport for any major US airline.