Coilovers are not cheap personally I would go for BC or Meister . I have heard you can adapt coilovers from an vw polo to go on the starlet think there's a thread here somewhere
Porting the original manifold is all ways good if your going after market I would go WEPR as above spot on service and the quality of the work is flawless. Tuning developments manifolds are good mate
Have you fitted an fuel cut defender before upping the boost? if you haven't your hitting fuel cut anything above factory boost setting your car will cut
Yeah that sounds like the right symptoms of oil seals wouldnt recommend changing the seals your self as the turbo will need a full rebuild in order to change them would just swap it out for an hybrid