Without seeing your bin, we can't tell whether you should add another tray. Leaving the top tray alone for 6 months is not a good idea. The worms will devour everything in the tray and you will have a thin layer of fully processed VC. The worms will be looking for another food source long before the end of the 6 months. Add another tray now if the lower trays look like they are pretty full of finished or nearly finished VC. Keep adding fresh food and bedding to the top tray for a while. If you really don't want to bother with them, maybe only feed every couple of weeks for 3 or 4 months. If you have a 4th tray, you can probably add it then.

Since you've taken it inside, just carry on with what you did when it was outside.
Maybe take more care to not overfeed since it's inside? (re. eventual smell and such)