Heighliners do not go into planetary orbit. They stay in space. Shuttles carry cargo and people between the planet and the heighliner.
Heighliners are not shielded. The Guild is neutral and attacking the Guild or a heighliner would result in termination of transport rights at a minimum, and likely other punitive measures as well. The navigator's prescience will warn of any unauthorised vessels approaching.
There are severe penalties for participating in combat or causing any kind of trouble whilst on any type of Guild vessel, including heighliners. There are armed security personnel on heighliners, but they are not normally seen. Few people can conceive of the concept of attacking the Guild.
In theory, a shield activated on a heighliner could interfere with the foldspace engine, causing the heighliner to deviate from it's projected track or dropping it out of foldspace. In practice, no-one has ever dared to try it.
Heighliners are a long, cuboid shape. A typical size is 41km long, 11km wide, 11km tall. The navigator's tank is 1km x 1km x 1km. It is sited on top of the heighliner, in the centre.
The heighliner is basically open to space. Its construction is a cubic lattice, the frame of which makes up corridors and lifts that passengers and the Guild's employees can travel along. There are attachment points for securing cargo and passenger craft, and access points to allow travel from craft to heighliner and vice-versa.
Each cube is 1km x 1km x 1km.
The foldspace engines are in the centre cube of the vessel. There are many of them. They shimmer slightly when in use, in a way similar to, but not quite the same as, Holtzmann shields.
The 26 cubes around the foldspace engines are enclosed, and consist of passenger and cargo space. Passengers and cargo are transported to these cubes by shuttle. There are differing levels of comfort at various price levels. Each cube is self-contained, with its own communal areas, food, bathing and sleeping facilities. Passengers within a cube may inter-mingle, but they will not be allowed access to other cubes.
Crews of cargo vessels and the like are allowed access to a cube.
Instead of travelling in the passenger space, rich customers may bring their own vessels on board. If a customer has brought several vessels, they will customarily be given sufficient access to be able to move between their vessels. The Guild often has some of it's own vessels on board. Anyone travelling on a Guild vessel will only be allowed access to the Guild vessel they travel on, much like the cubes.
People wait here for their cabins, or wait for friends to join them, etc. It is similar to a lobby in a contemporary expensive hotel.
This is a pair of rooms with a connecting door. One room has chairs, coffee table, shelves with film books. The other room has a bed and adjoining small bathroom.
This is a large room, with lots of tables. Each table has between four and six chairs arranged around it. Something akin to a large Starbucks/Costa. There are tables at the walls with drink dispensers, bowls of fruit, etc.
Large, communal cafeteria. Lots of large tables with bench seating. Serving area at one end, with serving staff stood behind trays of food.