I gather what we're talking about here is the Campbell line of HO railroad structure kits. I haven't seen any of them in quite a long time, but as I remember (from my days working in a hobby shop) they're made mostly of wood, with occasional paper and cardboard parts (e.g., roof shingles) and some plastic detail castings.
PolyScale works beautifully on such materials, if a little common sense is applied. If you put the model together with Elmer's Glue (which is water-soluble) and paint it normally with PolyScale (which is also water-soluble), there should be no problem; the paint dries really fast. If you use a wash technique to weather the model, and slather water all over it, the glue joints may soften up.
PolyScale works beautifully on styrene; in fact it's made for the purpose. On metal parts it works just fine, but a primer (e.g., Floquil) helps.
One difference you may notice, if you're used to Floquil, is that PolyScale, when applied to non-porous surfaces like styrene and metal, tends initially to be rather fragile. For quite a while after it's applied, it tends to rub or scrape off easily. Somebody who knows more about such things explained to me once that solven-based paints (e.g., Floquil) dry from the inside out, whereas acrylics like PolyScale dry from the outside in. They look and feel dry within a matter of minutes, but take some time (days) to really "grab" the surface.
I can really relate to the problem of smells. I grew up taking in for granted that a modeler's workshop had to smell like a mixture of turpentine, lacquer thinner, and Floquil Diosole. Then (this would have been in the early seventies, I think) I bought a few jars of Poly-S (the predecessor of Poly-Scale). Within a week or so I noticed a strange phenomenon: whereas I had been used to getting tired of working on a model after two or three hours at a stretch, I suddenly was having to make myself get up from the bench after four or five hours. I'd had no idea that the fumes from the paints and thinners were getting to me. I've been a fan of acrylic hobby paints ever since.
Hope that helps a little. Try 'em; I think you'll like 'em.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.