Engines are fairly good really, but oil leak from underneath is likely to be the oil seal on the gearlinkage, you can get a fix kit for it which is easy to fit. On the SPIs and the MPIs ecu and relay pack issues are fairly common, the relay packs are £100 new. The fuseboxes go all the time too, but they are only about £15, you can upgrade to blade fuses rather than the crap glass ones. Make sure any car you look at has the watersheild fitted, it comes off the rockercover and covers the dizzy, leads and plugs etc.