When installing over top of old ceramic/porcelain be aware that you will most likely have to "sink" the old tiles in cement to do this. That means grinding down the tiles a little (rough up the surface) then the self leveling cement is poured and allowed to dry. The new floor is then laid over top. Vinyl is notorious for requiring EXTREMELY flat surface. A ceramic tile rarely has this requirement (grout lines and "high spots" around tile corners give problems). A glue in place tile is also going to have the same problems and the same solution = sinking the tiles in cement. This adds extra costs to the floor. A rigid floor like a cork floating floor can handle a bit more floor deflection than vinyl or laminate planks. If labour in your area is relatively cheap...you could probably have the tile removed and the sanding of the mortar done for the same price as coating in concrete. You will also have the luxury of being able to lay any floor you want once it is done AND you don't have to worry about increasing the floor height. It is possible to sink the ceramic in cement...but is it the most cost effective option? Maybe not.

Sanded and polished timber floors have a evergreen classic appeal that never goes out of fashion. Carpet and other floor coverings do have a tendency to have a style that is relevant to a particular period in time. Have you ever walked into a home and thought the carpet, lino or tiles were from the 60s, 70s or 80s? Natural timber floors never date and you can easily update the look of your home with warming floor rugs and furnishings. Carpeted homes may pose problems for Asthmatics and those that suffer from allergies. There are a few environmentally friendly coatings available if you do choose to sand and polish your floors. This link will offer some insight into your floor coating options. http://budgetfloorsanding.com.au/timber-floor-finishes/ All the best with making your decision

I cant imagine that tiles on concrete will be any colder than concrete alone. But the choice of colour may make a difference to the heat absorption qualities; dark tiles will absorb heat better than light coloured ones.

The freestanding bath fillers are vulnerable to being knocked. When you think about the physics of it, it is asking a lot of a small fixture to resist that amount of leverage. Talk to your architect. They should be able to come up with a support that fits with your design and is a bit more robust than the long and thin proprietary bath fillers. Also how far is your bath from the wall? If it is closer than 300mm I would still be waterproofing the wall, and with young children around I would waterproof it even if further away.