I don't find specific answers to your specific questions, but maybe this will help.
There was a big lead and zinc mining boom in Marion and surrounding counties that began around 1880/5 and lasted until around WWI. Samuel Kirby may have moved here during that time (he's not mention in the Marion Co AR 1880 federal census) and left before 1900. I find his name in "The mining Era of Marion Co AR" by Vicki A Roberts published in 2003 "Hawkeye [name given to this placer claim in the Rush Mining District] recorded 30 Jan 1896 in the SW 1/4 of SE 1/4 and SE 1/4 of SW 1/4 of Section 27 and NW 1/4 of NE1/4 and NE1/4 of NW1/4 of Section 34 in Township 20 N Range 15 W. Located by M F Kirby, W W Fisk, A P White, J C Fisk, M D Tanksley, and S G Kirby." "Hawkeye - located on Clabber Creek and operated by Billy Crawford - was started in 1918 with a 50-ton mill, modern equipment, and sludge tables. Owned by Arkansas Zinc Co." Hundreds of placer claims were recorded in the various mining districts in the area.
"Marion Co AR Marriage Records 1896-1905" Samuel Kirby aged 25 of Flippin AR married Marion Co AR 23 Oct 1887 by J W Matthews Justice of the Peace Ellen Batman [Battman, Bateman] aged 15 of Flippin AR.www.genforum.genealogy.com
Battman Forum: #2396 Mandy Ellen Batman b MO 1883 d 7 Feb 1959.www.geneforum.genealogy.com
Kirby Forum: #4288 Samuel Grant Kirby m MO Ellen..