Depending on your char, there are 1-3 places where you need to either get good help or burn a small pile of wands to get it on your own. The worst black rod spot (you know where) I've never gotten more than three times on a 450hr char. Although, I also got it twice in a row. :(. When I get that one, I just look to clear it and don't care how many rods it takes. Just getting it to cycle. I suggest making friends with a bard or healer.

As far as rods changing location without you getting them, some location are in a desk, etc. and not on a mob. There spawn when you enter the room or area I believe and if that happens and you cannot find it, you'll get another location eventually.

As for the clues, different guildmasters will give different clues. So, that might help if the first clue doesn't ring a bell. Also, ask. I've helped anyone who's ever asked and AFAIK, I know all the locations. Others do as well.

Getting blacks pre-hero can be dangerous and on some characters, I just don't. You can probably buy them from another char though.