Indeed, moving nodes will use a fixed SF/power. But there is a fat chance that moving nodes will not use an optional antenna placement and thus have a very limited range.
Moving nodes are often 'labels' attached to objects like crates, trolleys or containers to track their position. It is expected that Spreading Factor and Transmit Power are set such that the highest possible battery life is reached while still allowing for a good enough range for tracking.
Do you also know the power setting used?
The LinkADRReq message in LoRaWAN (see section 5.2 of the LoRaWAN specification) will request the node to switch not only the SF but also the TXPower setting (+20 .. +2 dBm for EU)
Yes. As soon as there are more nodes communicating on the same frequency the noise floor will raise and signals with a much lower SNR will just drown in the noise.
But then, I still think the 95m high tower is a bit too high for this geographic location, apart from the fact that you will create a dead spot around the antenna location. Placing an antenna like a Taoglass on top of the 7 story high building (I guess about 30 meters) is a very good position.
In short, the "best position" always depends on the local situation. You always want a location to be covered by multiple gateways - this reduces the amount of lost messages due to interference, signal loss or gateway outage. Having 20 gateways placed on lower building in a city is preferable above just one placed on top of the church in a village.
Site surveys are an important method of determining where gateways can/need to be placed.