The fotospeed sepia is an odourless variety so OK for the kitchen from a smell point of view. However I would be reluctant to use chemicals in the food area in general and thiourea is a known carcinogen (can induce cancer) so be careful, be clean and thorough. It has not been shown to pose a risk when used conventionally for print toning AFAIK, but chemicals and food are a no no mix in general.
You can rebottle.
It will stop working well when getting exhausted. When you think this is happening, replace it rather than squeeze the last molecule out of it as highlight re development will suffer.
You don't need to re-fix provided you tone to the end point. If you pull early from the toner there will be undeveloped silver halide left and this will 'print out' in daylight over time unless you fix. In this case fixing may also lighten the print so I would never snatch early from the toner (unless after a special bleach look effect)
On the other hand you don't need to bleach fully and often the best results are from partial bleaching in a more highly diluted bleach. Then you keep the blacks black instead of brown and have a black/brown split, which can be v attractive. Its all a matter of preference though, not right or wrong.
Do make sure the prints are hypo-cleared and well washed before the bleach though, or tonal loss may occur.
I prefer to dry hanging. Others prefer screens. There are good reasons for either, but either will do fine.
Also, you may see a whitish deposit on the surface when the prints dry. This can scuff and mark and become more obvious with handling. If so, rinse in water with a little stop bath added and rewash.
Have fun. There are lots of little tricks you can apply to sepia toning to modify your results, but it is a very easy process.