B2N2, iaveight,
No you don't need a visa.
An I20 certificate is still needed as is payment of the SEVIS fee. See
here.
Technically you don't need a sign off for the FAA ATP check ride [...]
No practical testing is required for the conversion of a TCCA ATPL to an FAA ATP Certificate under the
Canada-US BASA and IPL.
[...] and formally you don't need any training.
S/he may need to complete the ATP Certification Training Program. See FAA AC 65-135A, Appendix I, table 3, footnote 5.
I have filled out the TSA form [...]
Why? Was this required for the ATP Certification Training Program, which is I assume what your 5-day course covers? FAA AC 65-135A, at 10(b)(4), states:
The pilot information that the FAA received on the form will be verified with TCCA. Further, the Transportation Security Administration (TSA) will conduct a security threat assessment.
[...]
(b) The security assessment conducted by the TSA does not satisfy the requirements of a foreign pilot training clearance. [...]
B2N2,
Since you have a "foreign" ATPL already there is definitely no 'increase in skill level'.
This is not an infallible yardstick for determining whether a security threat assessment by TSA is needed. The Alien Flight Student Program FAQ question #2 states for category 3 training events:
All other training events on aircraft with MTOW of 12,500 lbs. or less are exempt from AFSP regulations, including Commercial Pilot License (CPL), Airline Transport Pilot License (ATPL), and Certified Flight Instructor (CFI). These events are exempt only if the candidate holds an FAA stand-alone pilot certificate."
The security threat assessment in iaveight's case, using the BASA and IPL, will however be done in the background once he submits FAA Form 8060-71 (Verification of authenticity of foreign license, rating and medical certification).
[I]f you fail you do need a sign off from a CFI which requires training.
I'd be interested in seeing a justification for this claim.