I adore both Interia and Lo and Co Interiors for hardware. They aren't cheap but I wouldn't say they are super expensive. If you use some of their statement hardware, you could just do them on lower cabinetry and leave the upper cabinetry as push-to-touch and keep it simple and a bit cheaper.

Thanks for your suggestions. It is a hollow core door. Both sides are exactly the same to look at and when we use the good old knocking method, everything does sound the same. We might have to take the risk and do the work and hope for the best. We bought it from Bunnings. I'll go talk to them, see if anyone there knows any way around it.

Depends upon setup and surround of the pool area. Is the pool built yet or is this a retrofit? The most expensive options are the automated hard covers that are streamlined but require an extra section/length of pool to accomodate them. You can get recessed roller setups that are like a long trapdoor that conceal a blanket roller say in the deck or paving when it is not in use. You can build a hard cover say in the same decking material to conceal a blanket roller that doubles as a bench seat. Plenty of options but like all (design) solutions the most appropriate will come from analysing & understanding the context and budget we're working with

a very patient cabinet maker may be persuade to make a shelving unit attached to a super reinforced door on wheels with heavy duty hinges in an extra solid door jamb to carry the weight of a bookshelf let alone the contents BUT the bookshelf would have to be much narrower than the door to be able to swing closed and the gap on either or both sides of the shelf would defeat the idea of the concealed door...one option could be to hang the doors at the front of the fireplace to add a little extra space to the ens and wiw but that would probably spoil the look of the fireplace if it's similar to the one in the family room