It depends on the situation, but in some cases you can just use the inactivity for this. Meaning: inserters can't insert more into the train, so it goes inactive, and you know it's ok to go/leave.

Consider if the mod AAI Signal Transmission would work for you, then. It allows transmitting signals between surfaces. It has a cost - the receiver sender uses 10 MW.

You can open the blueprint library (B) in remote view. Place the planner and edit it there. No need to exit remote view that way.

I think you can solve this more or less by existing methods.

Request 10 normal construction bots in the roboport. If number of total bots > 100, grab those 10 bots and recycle them. That ensures a reserve.
If you just want to know total count of bots, request 0 of each bot quality in the roboport ...

A smart solution is needed. You can't just let the same inserter that inserts blue chips (for rocket parts) continue to insert blue chips as cargo. It needs to be two different inserters with different jobs. One inserter loads rocket part ingredients, and one inserter loads cargo.

What's an easy ...

A very simple addition would go a long way:

* Rocket launches when you input Checkmark as a signal

Starting small is the way to go with Gleba I think. Maybe I was lucky to find the way that way.

I started just with one agricultural tower, picking Yumako, mashing Yumako to seeds and replanting Yumako.
Create a few biochambers. Create basic nutrients. Discover that you need to use biochamber for ...

The biochamber in this orientation -- the lower part of the screenshot -- is drawing one of the pipe connections in a weird way. This is version 2.0.14.
The recipe is pentapod eggs.