Nope. I think your getting mixed up with fiberglass that is used to make boats, car bodywork etc. Rigid fiberglass that we talk about is simply compressed fluffy insulation, like loft insulation.
Yes rigid fiberglass or mineral wool. Bass traps are most important. You need rigid fiberglass/mineral wool, a frame and some fabric. You can find knauf rocksilk (mineral wool) pretty cheap here in the UK. I just bought a 4 pack of 4" Knauf Universal Slab RS60 for £18 at a local builders...
Abbey Road certainly has been acoustically designed with plenty of acoustic treatment. What you DON'T see, however, is a bunch of auralex foam stuck all over the place.
When it comes to control rooms, acoustic treatment is essential! For recording small rooms, like those is home studios...
Why not just record direct to the computer and not bother with the Zoom?
You could decent results recording each instrument separately with your setup as it is, as long as you are happy with only 2 drum tracks. You could either hope for a good mix on the fly for drums or, at the expense of...
My main clientèle in Ayrshire, Scotland are "Star For A Day" singers. I would rather record a full band, but bigger bands go to Glasgow and generally smaller bands are completely skint.