to answer your question, gh has a half life of less than 2 hours. so unlike test, your body won't shut down the process.
i belive gh to be much safer than any of the other gear listed in this post.
if money isn't an issue, run it 7 days a week as long as you can.
take 2ius injections 3 times per day with lots of test.
as for age, try it and see if you like it. the older you get the more pronouced the gains from gh. most say to wait until 30 year or older.