Re: Deploying the minibot!!
 

According to the Q&A I linked and <G22>, if the Minibot crosses the deployment line while deployment is happening and while it's still in contact with the Hostbot, the tower is disabled.

From the End Game rules:
Deployment only has one definition, as seen above.

So, to answer your questions in order:
1) When does the Deployment Line become effective, before or after the Minibot is attached to the post?
A: Before. It's kind of hard to initially break the vertical projection of the base and be attached to the post at the same time.

2) Is the volume defined by the vertical projection of the base and the plane at the same height as the deployment line a non-entry zone unless the minibot is below the line?
A: Yes. See the Q&A that I linked earlier.

The other question I'd have, that doesn't seem to be answered anywhere, is: If a robot's deployment mechanism requires the Minibot to go over the Deployment Line before Deployment (as defined in Section 1.6) begins, is this legal provided that when the Minibot enters the vertical projection of the base, it is entirely below the Deployment Line?

As written now: Appears legal (pending somebody asking Q&A).
As could easily happen: Appears illegal, depending on exactly how strict someone is at calling going over the Line.

Re: Deploying the minibot!!
 

A strict constructionist would say that the new wording of <G22> means that the MINIBOT can never be above the DEPLOYMENT LINE while in contact with the HOSTBOT - regardless of whether the MINIBOT is being DEPLOYED or not. In other words, you cannot store the MINIBOT on your HOSTBOT if any part of the MINIBOT is above 30" from the floor.

Someone will have to ask the GDC if this is the interpretation that they intended when this rule was revised.

Re: Deploying the minibot!!
 

G22 is under the 3.1.5 END GAME section, which begins:

<G18> All TELEOPERATED PERIOD rules apply, except as modified in this section.

Clearly, G22 applies to the end game period only.

If they need to clarify anything, it's what will happen when a high carrying HOSTBOT fails to lower the MINIBOT before the END GAME begins.

Re: Deploying the minibot!!
 

I think Jack and Gary's points both imply a need for more clarification from the GDC. On Jack's point: What if a team stores their Minibot high (say on a ramp) and decides not to deploy it (and never comes near a tower once the END GAME commences)? Because as the rule is written now that would clearly be a violation. But I find it difficult to believe that this is the intention of the GDC.