You should be ok realiablity wise with the fuel pump and injectors and stuff. I was going to get a swirl pot to carry on using mine as I think the fuel pick up on them isnt very good and I think it cost me an engine. Id be a bit worried about temps too now after having seen some readings from cars with guages, so id probably get oil and water temp guages at least to see whats really going on.
Im not the best at drifting (infact im not even good) and the RX7 is quite harsh from my limited experience (maybe Phil can comment, he drove mine for a little). By comparison I just jumped from it into my standard S14 and I can totally take the piss - its much friendlier. I probably did learn a bit from the FD though, but it is harder. As standard it has more better bits than most things I can think of but if you change them that doesnt count for much (LSD, Suspension etc). Not much steering lock though.
Its expensive to use. I spent £150 on petrol in one weekend last year just driving to tracks and back for double header. Its also expensive if you crash it. Id hate to think where youd even get a lot of bits from so I never really pushed it and never drove any slightly dodgy venues. This will change now next year (partly because im not so worried, partly because parts are easier for an S14 and partly because I think im a bit better now).
On the plus side you do stand out a bit at the moment as not many people will be driving one.
I found my HKS coilovers really nice on the road but a bit soft, but you have already mentioned sorting the suspension so thats covered anyway really.
I guess it depends how much you want to spend, how serious you want to be about it etc etc. I would say it is more than fine already for a few safe practice days to get your teeth into and go from there.
Err, I think ive answered but in a waffled unstructered way. I guess Id prefer something more specific to comment on
Lee