Hyperoptic 1Gb - some questions

I'm thinking of changing my ISP to Hyperoptic to get FTTP speeds. Before I moved house 2 years ago, I had 900Mb/s FTTP from BT, but they are unbelievably slow in rolling it out to my new home area. Hyperoptic are offering 1Gb speeds here but, before going with them, I need to check other people's experiences. So, can anyone help me with the following:

1. What's the max number of supported devices on the supplied router? I have a lot of IoT/home automation gadgets and frequently have over 30 devices connected simultaneously.
2. Has anyone switched phone service from BT to Hyperoptic and been able to keep using the BT smart handsets, i.e. the Alexa enabled ones that work with the SmartHub2?
3. Installation experience: I live in a 3-storey town house and my existing BT main socket is one floor up and at the back of the house. Has anyone been in a similar situation and did Hyperoptic run fibre all the way to the existing main socket location?

Thanks in advance for any help,

Steve

1. No idea, but you can use your own router, apparently
2. Keep your existing phone until you are happy with the service. Then get an ATA and a voice service from an independent supplier such as Voipfone. That way, your telephone service never gets tangled with ISPs
3. No idea