1. There is a special tool for this, yes, but I don't think you need to use it. I've not done it, but if you can't get it undone, it's usually suggested that you brace a breaker bar against a bit of the chassis then briefly turn the engine over to apply the leverage to loosen it. Edit - see this thread.
2. Don't know how similar it is, but I think your mechanic is thinking of the 4-cylinder 3S-GE engine, which is in the Altezza RS200, rather than the 6-cylinder 1G-FE in the IS200. I'm sure he won't have any particular problem though.