Bandwidth used for community server?

As a new user I have multiple questions, I will try to break it up by topic.

Part 2

I have a couple servers that I may be interested in perhaps donating one of them to the cause by letting others use it as well since I am certain my own utilization will be minimal, but would like to know what kind of traffic the average tile server transmits. Here are the specs

Server 1:

1. Dell R620
2. Perc H700
3. Dual X5680 @ 3.33GHz (6 core / 12 thread per processor)
4. 192GB DDR3 RAM
5. 4X 146GB 10K drives for OS
6. 1 256GB PCIe m.2 SSD for /var
7. 100GB Fiber Internet

Server 2:

1. HP dl380 g5
2. Perc H700
3. Dual X5675 @ 3.07GHz (6 core / 12 thread per processor)
4. 96GB DDR3 RAM
5. I honestly don't remember the config of the HDD setup, it has 24 slots, all are filled with either 10k or SSD.
6. 2TB of SSD storage
7. Bonded 2GB network connection

Server 1 hasn't been used at all and is at my office not a datacenter, Server 2 has been a Wowza video hosting server at a top tier datacenter in Utah for me for the last 5 years which has some extra bandwidth available, either way, I would need to know more about what traffic / bandwidth to expect.

The map I personally need is not a highly detailed map, I don't need mountain peaks names, forest trails, canals and so on, just a basic map with major roadways. I am not sure yet if this is controlled by the osm2pgsql import, or by the tile server, are the tiles generated on the fly based off the URL requested, or are they all pre-processed?

The customers I need to be able to geolocate are currently only in the North American region, but if to be included as a community server I need to host the planet, I could probably swing it, though it looks like server 1 would need more storage space on the SSD if I needed to do the planet (https://help.openstreetmap.org/questions/64405/tile-server-hardware-requirements).

Can I host my low detail along with the normal higher detail that most people use or do I need to decide and stick with it? When searching the forums I found the option --flat-nodes which intriqued me, not sure yet how to generate the type of map I want, but that option made me think that it was during the data import, which would mean I couldn't do 2 types of maps on the same server.