Here "stumbling" is a metaphor for sin. AT: "things that cause people to sin ... things come that cause people to sin ... any person who causes others to sin" (See: rc://en/ta/man/translate/figs-metaphor)
Jesus exaggerates here to emphasize that people must do anything necessary to remove from their lives what causes them to sin. (See: [[rc://en/ta/man/translate/figs-hyperbole]])
All occurrences of these words are singular. Jesus is speaking to all people in general. It may be more natural for your language to translate with a plural "you." (See: [[rc://en/ta/man/translate/figs-you]])
# into life
"into eternal life"
# than to be thrown into the eternal fire having two hands or two feet
This can be stated in active form. AT: "than to have both hands and feet when God throws you into the eternal fire" (See: [[rc://en/ta/man/translate/figs-activepassive]])