Chinese GH is ok, some of it anyway. We can't discuss brands here, but check out some of the other BBing forums, do your research for a little while. It quickly becomes apparent which brands are gtg, and which are to be avoided.
That being said, I've got Greek GH now, and I have to tell you, I am getting the same sides/effects at 3iu per day, as the Chinese stuff was giving me at 5-10iu per day.
If you get a good brand of GH, you shouldn't need more than 3iu per day, unless you are REALLY trying to get huge jacked, and money and acromegaly are no object lol. I just take my 3iu first thing in the morning, and run it for 5 days on, then 2 days off. But that's your call.
As for your questions:
Question #1: GH almost always comes in vials of 10iu each. I reconstitute with 1ml of Bacteriostatic Water, but you can do 2ml's, which will make it dissolve and go into solution faster, your call. If you use 1ml of BW to reconstitute, the a 5iu dose will be .5ml. If you use 2ml to reconstitute, then a 5iu dose will be 1ml, and ect. Some vials are 4iu, some are 8, depending on what you get, just do the math accordingly.
Question #2: From all of what I have read, 5iu is a "safe" dosage, giving good body recomping effect, without the risk of acromegaly, or gut growth (the jury is still out on whether GH gut is real or not, or whether it is caused by GH when it occurs) that being said, I ran mine for 6 months or so, at 5iu per day, and I noticed my jaw get ever so slightly more square. It was a welcome improvement, but something I definitely kept an eye on.
Hope this helps you out bro, wish you all the best.