It sounds so exciting with the loom
I know the difficulties of moving those monsters. The carding unit I had in Denmark was an industrial one and I was offered looms as well. I just didn't have room for one. They went for scrap - what a tragedy.
As to fibre. Your challenge on that type of loom will be having a strong warp thread so it is best to buy that. Stay away from linen as a starter as that needs the right moisture to keep it's strength. ( Sorry my weaving language is Danish)
As to weft, homespun wool would be fine. With weaving you have the advantage that single ply works well as the threads go from left to right then back again so the "bias " gets evened out.
I can sometimes cadge stuff from Bradford when I go to order carded tops . I will see if I can cadge some thin woolen yarn suitable for the warp thread. But that will not be until May.
When I wove clothing type material I span both the warp and the weft single and wove in the grease. Did not weave it tightly then I fulled the cloth. I was not good at it , the finish product was pretty thisk but great for "lumberjack" type shirts.
If I were to do it again, I would spin the weft from 50% wool, 50% tencel, the most environmentally friendly constructed fibre on the market at the moment. It is made from eucalyptus, can be spun very thin and is so strong
Following yours adventures with the loom with great interest,
Yours sincerely Renee.