If I remember correctly the thing about thickness is one of those "pauses before blowing" ideas.
Seems that if you wait for a four or five count after taking the glass out of the flame, the thicker parts will retain heat and still be kind of plastic and the thinner parts will have cooled enough to stiffen up some and wont be as plastic so they won't get thinner with the pressure of blowing.
But that is one of those "once you have made 100 of them the timing thing seems to fall in place" kind of deals.
So go ahead and make 100 of them, use one color of glass so you can recover the fragments and reuse them with out concern about the mixing of colors.
Oh and different colors are going to have different heat loss and retention characteristics so you probably want to hold off mixing patterns and such until the shaping techniques get comfortable.
Isn't it a wonderful addiction?