1. Its part of the ignition lock housing, not a seperate part. Job isn't going to be easy cos of the column spline adaptor, either use a good set of pullers or tap the end of the column with a hammer (thread the nut on to protect the threads) the column will colapse and the adaptor will pop off, then extend the column again & swap the ign lock housing.
You need to drill a small hole in it to swap the lock over, but thats all covered in the above link.
2. All MK2 subframes are the same

3. Replace the blue temp sender, then follow my digifant tuning guide in the MK2 maintenance + info section. If you don't have a timing light and/or a CO meter, print it out and hand it over to the local garage so they set it up properly!