In Canada, in the major jurisdictions I know of anyway, and certainly in Federal and BC Provincial elections, the ballots have a list of the few candidates that are running in your riding (sometimes as few as three, rarely more than ten if the Rhino and other fringe parties managed to field a candidate), and no other issues are decided on the same ballot. Referenda, if they happen to come on the same election date, are on a separate ballot. Federal, Provincial and municipal elections are all on different dates. I don't know if write-in candidates are permitted, I don't think so as they have to be supported previous to the election by a minimum number of registered voters.

Each party can have a representative at the polling station to oversee the process.

As I mentioned, ballots are paper forms (with a black backing over the voting area) on which one marks an "X" as indicated clearly by a poster in the polling booth. Parties generally provide interpreters in high ESL areas.

Seems to work OK. There are mandated recounts if the margin of victory is within a certain amount.