first of all, export is not considered as backup it is just logical backup.

1. you can not restore the DB using logical backup so no use of archive logs if you are taking ONLY export backup.

2. backup strategy depends on your DB size. If it is small, yes you can take full DB backup every day. If it is big, then take the backup of archive logs every day then DB full backup on weekly basis or Incremental backup on daily basis

3. correct. you can incorporate this in archive log backup script or if you are taking full backup you can incorporate the same in the DB backup script.

Thanks,