Yes the 50 credits is what you get for advancing tiers.
The redwood putter is by far the best club to buy. IMO.
As for clubs, I would wait until you make pro. My reason is this. You only have 5 ranked rounds. Closest to the hole comps do not count. You average(that is what advances you though tiers) is based the best 10 of your last fourteen. If you continue to play the way you are you will be a pro when you have played 10 rounds. That will open up better equipment as some clubs are restricted to tiers.
Hope this helps.
*edit* If the rapture set is what you are looking for (good clubs) they are available to you now.