At least when the reboosts were done using the shuttle, there was no procedural call out to secure anything.
This answer steps through the procedures and includes links to the full text of both shuttle and ISS procedures.
How was the Space Shuttle Orbiter used for ISS Reboost?
You have several kinds of radiation to deal with:
Sunlight. Sunlight has a fair amount of UV. On Earth most of this is blocked by the ozone layer. Only a fairly small percentage gets through. Hence all the fuss and feathers about chloro-fluoro carbons (freon and friends) breaking down the ozone layer. On Mars you don't have enough free oxygen to form ...
The crew of the nonfunctional spacecraft would have to wait
escape capability until a Soyuz replacement or a Shuttle arrives (either of which could
take days to months depending on timing).
(Nowadays read Crew Dragon for Shuttle)
Final Report of the ISS Independent Safety Task Force p.52
They did, but its use case was pretty narrow.
The shuttle hatch was modified to be able to be explosively jettisoned, and a telescoping escape pole (pictured below) could be deployed that would help bailing crew members clear the wing on the way out. The vehicle, however, had to be in a stable glide and below 25,000 feet, which pretty severely limits the ...