everyone is invited to help, in the good spirit of free software.

How would the previous sentence be correctly capitalized?
Answer: Everyone is invited to help, in the good spirit of Free Software.
the traditional kids cupwere, as usual, played saturday morning at konventum.23kids participated in the four age groups u08, u10, u12, and u14.

How would the previous sentence be correctly capitalized?
Answer: The traditional Kids Cupwere, as usual, played Saturday morning at Konventum.23kids participated in the four age groups U08, U10, U12, and U14.
ingestion of a caustic agent, or poisonous plants

How would the previous sentence be correctly capitalized?
Answer: Ingestion of a caustic agent, or poisonous plants
and the same goes for emissions of climate-impacting carbon dioxide and other substances.

How would the previous sentence be correctly capitalized?
Answer: And the same goes for emissions of climate-impacting carbon dioxide and other substances.