1. Presumably a fibre network can easily handle the bandwidth to distribute satellite or cable HD signals (Sky HD and, when available, Freesat and DTTV HD)?
Easily -
2. Can the same physical fibre carry multiple AV sources (e.g. DTTV + Freesat + Sky) simultaneously or does it have to be switched? If it can how are they multiplexed/demultiplexed?
Yes - Fibre can carry multiple signals at different Wavelengths (different Colours).
3. Similarly, can the same physical fibre carry both AV and an IP network simultaneously, if so how?
Different Wavelengths.
For example..
1550nm - Video
1310nm - Data TX
1490nm - Data Rx
4. What kit do I need at the central point (to convert DTTV/Satellite/Cable signals to fibre) and the individual nodes (to convert back to feed into the satellite or TV receivers)?
ODU 32 from Global Invacom will allow you to put DTV/DAB/SAT on fibre...
http://www.globalinvacom.com/products/Wholeband.php
5. Who are the main manufacturers of this kit (for serious home or small commercial - e.g. hotel - use), not hobbyists (it needs to be reliable with minimal maintenance)?
http://www.globalinvacom.com/products/Wholeband.php
6. What order of cost am I looking at?
Depends - if it is just sat you want to put over the fibre you could just use a Fibre LNB & a box at your set-top.
around £150 each end..
Fibre is similar per M as coax.
7. Is this a sensible approach or should I really be sticking with coax to each node, in parallel with a Cat5e or Cat6 network for data/phone use?
Fibre all the way
But I would say that
A lot of questions - but I'd really appreciate some views on this.
My main motivation for going the all-fibre route is that this is a major and messy re-cabling project I only want to do once, and I need to future-proof it for all potential sources/uses (and also agaionst the possibility of fibre to the home eventually).
I would suggest you future proof your installs by running in a fibre alongside your coax/Cat5e