Looks rather like elecampane, Inula helenium. Mine (also in Western NY) are in bloom now. It spreads by wind blow seed and starts blooming in its second year. FataMorgana

Hostas? I had thought of planting hostas under bamboo, but thought shooting might be a problem. Were it something like H 'Undulata', who really cares, but if a shoot came up in the middle of a big, mature H sieboldiana, like 'Elegans' or 'Great Expectations', or some other desirable slow-grower, my wife would be most unhappy.

For clumpers, the largest species never seem to get enough water. I've added various stuff to soil to get more water retention, but they just don't seem to like it. Found this to be true for D. Giganteus, Asper, Brandesii, Oldhamii and a few others. They seem to perpetually have curled leaves during the summer, even if you water daily. Vittata is pretty successful for me in pots. So far, Atro and Lako are doing well, although they are both pretty small at 10-12 feet. Mex Weep is a great container plant. It seems to be about the most drought tolerant bamboo I have found. Same is true for O. Acum. Acum. As far as runners, S. Fastuosa does well for me in pots. Don't even touch any type of hard/brittle pot, like terracota, without a plastic pot inside. The roots will pop it in a heartbeat. As far as how big, all depends on the species and how big the pot is. Everyone has their own experiences, but I doubt you'd get a large clumper over 1/2 of the ABS reported heights. For some of the largest, might be more like 1/3 (like D. Giganteus, Asper, Brandesii, Hamiltonii, etc.). If in full sun and fairly warm weather, use water retention material.

Local extension services tend to have differing opinions from the above :-) Iron deficiencies are not always tied to alkaline soil conditions - in fact, soils that are only mildly acidic (a relatively common PNW situation) tend to bind iron, making it unavailable for plant uptake. That's why fertilizers forumlated for acid lovers - rhodies & azaleas, camellias, blueberries, etc., all tend to have a significant iron component. Conversely, highly acidic soils have the same effect re: iron availability but through antagonism with other nutrients, typically aluminum and manganese. As to how effective iron supplementation may be, it only takes a quick application of chelated iron (or Miracid) and the resultant almost instant "greening up" of the foliage of virtually any pale broadleaved evergreen for justification of its use.