I'll try to answers all your questions...
"any other alternative other than using the fibreglass mesh.."
This is what I have experimented with and it works well... I have not tried anything else. Let us know of the results if you do try something else...
The mesh is always contained in wax so there are very few opportunity for fiber dust to become airborne, except perhaps when you first cut the mesh for your first wax mold.
"difficult to get out here.."
This is found at ship shandlers, surf shops, boat shops, most hardware stores should stock it too... It is a bit dear but you do not need much and you can reuse it many many times.
"it is still strong enough to hold plaster?"
I have only cast Forton in such molds and it is definitively strong enough, stronger than plaster gauze mold I feel. Even though I have never cast plaster in such molds, I think it will be strong enough for plaster... Again, report back with your findings If you do cast in plaster..
"ok to rest it on a pile of old clothes too.."
Absolutely OK. I do it as amatter of fact, an old habit, because "I have always done it that way" but I suspect that the mother mold is strong enough not to require any support. If in doubt of its strenght, you can always reinforce it with more wax before casting anything it it.
"fill the mold & cast with wax? "
Casting wax in Alginate is perfectly fine. I have done it many times... If the mother mold is made of plaster bandages, the wax will not stick to it (because the plaster is full of water, water and wax repel each other.) If the mother mold is made of wax, It is possibe that the cast wax will stick to the mold's parraffin. Again I have not tried this yet with a wax mother mold but I suspect that it should not present too much of a problem; No more of a problem that cast plaster sticking to plaster bandages.
I have just completed a large pregnant belly mold with the wax technique, in half the time it would have taken me with plaster bandages.
The only problem with this method is that you need to spend some time to recycle your wax mother mold. A plaster bandages mold is simply discarded in the bin. You must remelt your parraffin mold, pick up and drain the fibreglass mesh (I pick them up and dip them in a bucket of cold water to cool them quickly) and then filter all bits of alginate and cotton wool out of your batch... Then it is ready to use for your next mold.
I am keen for people to try it and see how we can improve the method... Two things to watch for:
1- make absolutely certain of your wax temperature... anything above 50 Celsius and the model will sue you for attempted murder... I use a shallow frying pan for constant and consistent temperature, not a deep crockpot as the wax can be cold at the surface but hot at the bottom.
2- Hairs get trapped in wax but that is not different from plaster...