First of all, check WES online assessment tool, to see whether the results satisfy your needs. (This is important)
Now following are the statements, that are given in WES site, regarding to your Q's and General Facts gathered.
1. Mark sheets attested by persons outside the Controller of Examination or Registrar's Offices, such as individual professors or external notary publics, will NOT be accepted.
2. WES requires that all documents be issued and attested by the Controller of Examinations.
3. College-issued and attested mark sheets will NOT be accepted unless it was and still an autonomous college during the period of study.
4. In TN all certificates are verified through directverify.in, see if there is that service available for your college and university, After this process you've to go in to get it sealed and signed with a cover and the academic records request forms to be attached.
5. If required, Transcripts for programs attended in Autonomous Colleges are provided from College itself, Not from Universities.
6. Autonomous colleges do not award final degrees, the affiliated university does it; It is only said that marks sheets alone attested by the autonomous college is acceptable, In some cases colleges also offer to attest the degree certificate.
7. Yes, you've to attach "Academic Records Request form", Even if the University is ready to send your documents without it.