I have a portulacaria afra myself. It sounds like you got one at Loews, or somewhere similar, since there was gravel on top of the soil. removing it was a good move. I never understood why they glue rocks on top of the soil. I think this is to mimic the fact that most true bonsai are grown in a very granular soil. As far as portulacaria afra care goes, I keep mine in a southeastern facing window that gets direct sun. I had it in an eastern facing window for a while and it did poorly, I have assumed that this was due to lack of light. So be sure to give it as much light as possible. during warmer months if you can put it outside, then that will help it. those trees you see when you google portulacaria bonsai get alot more light than even mine does. that is why they grow so lush and compactly (the lush growth may also have to do with fertilizer). In terms of watering, portulacaria is a succulent, so it can withstand some drought, but it seems to be less drought tolerant than actual jade is. mine dropped its leaves once when I went too long without watering it. but you should let the top of the soil dry out before you water it. On to soil, typical bonsai soil is basically some sort of small gravel, maybe with woodchips or other large organic particles. However, I am an amateur and find that when I grow the easy indoor bonsai species such as portulacaria or ficus, they don't mind having regular potting soil. I usually buy the miracle grow potting soil from the store and mix it with perlite at about 1:1 ratio. my jade, and portulacaria, and ficus are all growing healthy and fine, even with reduced root balls. both crassulata (jade), and portulacaria are great plants for a beginners. This is because they grow in a very beautiful, bonsai-like fashion without even requiring much training. I have a 4 year old jade tree in a regular size pot that is incredibly impressive and looks like a miniature tree without ever having been pruned or trained. just make sure that you give it lots of sun and enough water. I am a beginner to bonsai when it comes to pruning and training, but my advice would be to worry about growing the plant normally first, and once you see that you can take care of it without training, then you can start experimenting with pruning and training. I don't know how much general plant experience you have, but it may be a good idea to try re-potting your portulacaria in a normal sized pot and try growing it For a year or two in that pot. Then maybe try pruning it down to bonsai size. it is a good idea when you start experimenting with training a bonsai to take a cutting of the plant to root a new baby plant, so that if you kill the parent plant you don't have to go out and buy another one. I do this all the time now. anyway, these are the things that I have found work best. Bonsai, in my experience, is not something you can just do. It takes years to get good at it. You will make mistakes in pruning, and you will kill plants, and you will have to wait months in order to overcome your mistakes. I did a bad wiring job on one of my trees two years ago and the scars are still visible . . . On the other hand, for most of the year all you need to do is water and occasionally fertilize your plants, you only end up doing the hard work once or twice a year depending on how much your plants grow. Good luck with your new plant and if you have any other questions let me know!

Your questions are probably better suited for the Container Gardening Forum, link below Here is a link that might be useful: Container Gardening

What makes an excellent top dressing for plants is white Gran-I-Grit in Grower or Turkey size. It's heavy, so won't blow away, and the white surface not only reflects light (which turns to heat if it contacts dark soil) to help keep root temps lower, the added reflected light helps keep lower leaves of plants working more effectively, which means plants retain them longer, remain fuller, and realize more of their potential. Anything else that would be heavy/white/reflective would work as well, but the grit is prescreened and requires no additional effort other than perhaps rinsing off any dust. Al

If it has roots and you didn't chop off some thick roots, you can pot it and start watering immediately. They will tolerate a good bit of water in an aggregate medium. I have to disagree with Josh about their drought tolerance though. I have 8 foot tall ones in the ground and I have 4 foot tall jades in the ground on a southwest facing hillside and the C.ovata definitely show signs of drought first. They both have the same exposure and they are both well established as in decades established. edit: I noticed Josh mentioned defoliation. Yes P.afra will defoliate before C.ovata in response to drought, but that just makes the plant more drought tolerant.