Re: 3 questions
Some answers:
2) Have a look at UpgradeTo19. But remember 1.9 is still in development RC code, and currently is not meant to be used in production unless you can bugfix Tiki
3) Its possible, a lot of tiki-s outgoing email is classed and picked up by spam filters. Best thing to do is have a notice on the registration page saying please add (your tiki senders email address) to your whitelist before registering.
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