well, my guess is that they are all in pretty bad shape when all is said and done. you could get your hormone levels back to normal with HRT, but on their own i'd say it is nearly impossible at that point.
as for kids, I would think that their sperm coutns would be too low for the most part to concieve a child. It all depends on the extent of abuse and whatnot. if you were administering HMG (not HCG!!) during the useage, you would most definetly be able to have kids. (HMG keeps FSH function in tact, which in term keeps the body producing sperm). of course you can use quite heavily and still have kids though -- arnold comes to mind. but there is a point when I beleive you could do permanent damage.
the GH gut is pretty brutal. you should see Dorian Yates nowadays. I had the oppurtunity to see him and after dropping down to 215-220 his gut is way out of proportion to the rest of him and it just looks plain gross.
these guys have bigger problems to worry about then having kids and GH guts though. there internal organs are undoubtably in terrible shape from years of high bloodpressure, bad cholesterol, and excessive diruetic useage (<< flex wheeler comes to mind here -- his diruetic useage cause most of his health problems).