"The Ultimate Unit Bearing, the last bearing you'll ever need." until you need a new one anyway.
5/8 is the diameter of the stud not the length, you cannot cut it or rethread it to make it fit
sucks they don't make them to order anymore. pretty sure if they make them for you they will fit, it's a simple process drilling and tapping 1/2 inch 5x5.5 holes instead of 5/8 holes
5 years is a good lifespan for the hubs, i think they lasted me just under three years with 140lb rim/tire combo
if you need to look long term though, can ask Billy and he can tell you how/if you can switch to a rebuildable hub.. I think his were 6 bolt 5/8 though... or get new rims for next time with 5/8 holes