Rental Suite - bridging -v- Telus guest network -v- switch??

Query 1: You said "keep in mind anything connected to the switch has a direct outside connection". I wondered if there was some risk/issue to worry about here that you were thinking of?

Only connect a router to the switch. You don't want individual devices connected to it for security reasons. Additionally since your connection is only alotted 2 IP addresses, if you start connecting additional devices, they will fail to connect. Bridging would still use a second IP but it wouldn't allow additional ones unless you change the router or device connected to the bridged port.

Query 2: Is there a "risk" to having the walled connection in the suite "live" running directly to the switch?

I'd stick to just offering them wifi. You can configure many routers to only allow access to log in to them over ethernet connections. That way if the users are on wifi, they won't be able to try log in to the router and mess with things. There are some third party routers that you can get that specifically have settings for guest suites / networks. If you did put an ethernet jack into the rental space, you could still have the router outside of the rental space and just have the ethernet jack connected to it instead. Direct physical access to the router would be a bad thing. I would not put the router inside the rental space.

Query 3: Similarly, if the new wireless router itself is in the suite, is this more risky as guests have physical access? I'm not sure I have a choice, but if there was a wall connection in the main house close to the suite that I could use, instead of placing the wireless router directly in the suite, is that something to consider? (this way they cannot plug directly into the router and mess with settings for e.g.) Or this this me just being over-the-top? 

Direct physical access to the router would be a bad thing. 

Query 4: Would you be able to explain in simple terms why the switch might be more secure than the bridging?

Because the switch would be two physically separated devices / networks. People have had isssues with bridging in the past under certain conditions so a switch and separate router would likely minimize issues. You could always start with bridging to see if you have any issues. If you don't, then you could leave it as is. If you do, then get a switch and go that direction instead. 

Query 5: What would happen if I had faster internet that Fibre 250? (I have Fibre 250, but others might have faster, and I am also curious - as I say this is super interesting!)

With a gigabit switch before the Telus router, the max speed you could get is gigabit. If you ever wanted faster than gigabit, then you'd have to look at a 2.5gbit or 10gbit switch, which are more expensive. Though the more likely scenario is the NAH with the 10G port would likely have to move to where the fibre itself is since that's the device used for connections faster than gigabit. Unless Telus has a newer ONT capable of faster. The ONT I have only supports gigabit. The ONT is the device that converts fibre to ethernet.