If it is just the valve stems, don't panic, I drove around for 18 months on my last 1G with leaking valve stems. It is just a sign of the engine ageing. If you don't mind a puff of smoke on startup then don't worry about it. If you do, then fix it. The joys of owning an old car mate.
If your seals are just starting to go, then you probably wouldn't notice the small amount of oil loss, so just do your normal oil checks and you shouldn't have to worry any more.
The "smoke" on boost is probably just the engine running rich and it would have done this since new and you haven't noticed until now. It may be your turbo oil seals but we can't tell unless we see it.
If you are concerned, why not take it to a mechanic and get him/her to look at it. They are not all evil you know.