Apart from gridding the house, should the kitchen be gridded separately?
Yes. Interior vastu means zoning each room separately with its own grid and then designing its interior accordingly.
Related questions
Can artificial plants be used in the kitchen?
Yes, there is no problem in using artificial plants in the kitchen.
How do we choose a direction when no planet in the chart is exalted and several planets sit in one direction?
First choose the direction of exalted planets. If none are exalted, go towards the direction where the benefic planets sit: Venus, Mercury, Moon and Jupiter are benefic, while Rahu, Ketu, Saturn, Sun and Mars are malefic. Then use the interior items, seed mantras, artifacts, statues, trees, colours and symbols, to strengthen the planets that are not exalted.
How is an individual room gridded?
Treat the room like a house: for a 10 x 10 room, for example, take the centre of the room and draw the grid from there exactly as for the whole house.
If one family member has a planet exalted and another has it debilitated, should that planet's items be kept in the interior?
Decide room by room. In your own bedroom use the materials of your exalted planet and not of your debilitated one; your daughter's bedroom is designed from her kundli. The house facing and common areas such as the drawing room and kitchen are decided from the grih swami's kundli. Many people make the master bedroom in the South-West by default, which is wrong when Rahu is debilitated: such people suffered there and got very good results after moving to another direction.
Is the direction of the whole kitchen considered, or only the direction where the burner is placed?
The place where the fire burns matters most in a kitchen, so the direction of the burner is the key one.
Large glass panes now fill whole walls instead of windows. Do they count as windows, since the window pada chart cannot be applied to them?
With UPVC systems whole sections can open, so at least open the part that has an opening system, wherever possible. Following the allowed span, the East from E1 to E7 can be opened fully, at least five padas of the North, three padas of the South and three or four padas of the West.