Hey M, glad to hear you're excited about giving Tendon a shot. Appreciate you sending these questions too, as they give us a good idea of what we can improve on in the rulebook going forward.
1. By far the most consistent feedback we've had on Tendon is confusion regarding the map layout. (Something we're working on improving for updates) Here's a quick example of how it works for clarification:

When you enter a new square in your player book that is not filled in, it qualifies as an Unexplored space and you roll 3d10 to generate the room. The room is the combination of the visual description, the harvest available, and the shape you get from the table.
The "Navigable" label corresponds to the path you can travel up until the next Unexplored space. Anything crossed out with X means you cannot interact with it or generate a new room there. (In this example I've color coordinated them for clarity)
In regards to Harvest and Seed, there is a new Seed per square, but the Harvest is tied to the 3x3 room you generated. This turns into each 3x3 space as a sort of micro-habitat in the largest ecosystem, making managing inter-Seed dynamics a little easier for your Nurse.
2. Great question about overlapping hours, and I'm glad you like the asynchronous system! In our testing we've (so far) relegated it to house rules with how overlapping spaces are managed.
- Some groups have preferred having a single Graft that's reliant on communication for what each hour looks like, doing check-ins to see if someone has explored, say, 8am yet and if they have what it looks like so far so that someone else can pick up where they left off.
- Others lean into the weird elements of overlapping time, allowing room layouts and Seed to spill into each other whenever they run into a scenario like this. Of the two I'd say this is the more chaotic and deadly, since you're increasing the likelihood of propagation.
3. Multiple party members can contribute to a contested action if it's reasonable within the narrative. If, say, you're both using Force to heave a giant limb that's pinned you down, you'd both roll and use your pooled results to find matching numbers. (It's far easier for Nurses to die alone than together)
In your case with multiple people attacking separately, then you would not combine your results and simply have them play out in order of speed. Here's an example scenario to illustrate:
- You and your fellow Nurse are within close range of a Seed as it barrels towards you. You both have a rifle-based tool that requires Touch to operate. For the Seed's behavior, you use its generation table as a baseline. Lets say this one has Sprinting, so you assume it wants to ram whoever is in their line of sight. In this instance, its you.
- You roll two 8s, your companion rolls four 2s. The Seed rolls three 5s. This plays out:
- Your companion shoots the Seed in the leg (2), and it takes appropriate damage. It stumbles, heaves forward and collides into your chest (5), knocking you back before you have time to fire your shot off.
- Next interaction begins.
If any more questions come up during your sessions, feel free to send them my way.