welcome to owning a porsche. as soon as you realize it is just another car it will be easier to work on. don't be intimidated because it is a porsche.
i 100% agree w/ swivel everything. swivel sockets in 1/4 and 3/8, swivel ratchets, swivel spark plug sockets, swivel gear wrench, flexible shaft nut drivers. Further more, i 100% agree w/ an assortment of long *** extensions, but will one up it and say to get locking extensions.
swivel spark plug sockets to remove plugs, to install, i use a cut piece of rubber hose to hand start and then use the socket. the locking extension comes in handy b/c don't have to worry about the socket getting stuck. You want to make sure you don't cross thread the holes-- it can happen very easy hence why i start by hand. also, when you put the wires back on, be certain you hear the "pop" of it connecting to the spark plug. it is easy to not be on.
locking extensions wise, i have the mac 1/4 and 3/8 sets. they were thinner than the snap-ons when i bought them. stuff may have changed since then though.
for doing belts, a good adjustable pin spanner to get on the shroud-- ebay is good for this. to actually get the tension of the belt, well that is trial and error with the shims.
you mention a you own a turbo-- so the intercooler pretty much has to come off to get to everything. flexible shaft nut drivers are nice for the intercooler hose clamps (i have wiha's set), and long locking extension w/ a 13mm swivel w/ some sticky windshield buttle (spelling?) stuck in the end of the 13 helps out. actually, go get some buttle--as you will end up using it as a cheater to hold nuts in place in sockets. buttle is the black sticky gooey gets everywhere on your hands stuff they use around windshield seals. it is more awesome than tape in a socket method.
the 2 most important flex head ratchets i have that i use are both snap on. one is the flex head 1/4 inch ratchet. the other is the exact same body, but w/ 3/8 guts. they are compact enough they go any/every where. if you need to be more shallow than a flex head ratchet, thats where the flex head gear wrench comes into play.
if you plan on doing work to your own car, wouldnt hurt to buy the rear apron fender cover setup. it goes from the left 1/4 over to the right 1/4, and clips inside the wheel well and engine bay. it is nice because you can unhook the ac compressor, and flop it over the left 1/4 on the pad w/o worrying about scratching paint.
assenmacher tools makes a kit that has real shallow 1/4 drive allens/torx/phillips etc that is worth picking up. part number is ast 3000 iirc. or you can buy hazet brand ones for much more money.
other stuff worth having-- bottle of loctitie 574, jb quick, and gray permatex. those 3 items will cure alot of oil leaks if used properly on a air cooled engine. a stock of various copper seal rings helps too.
if you plan on dropping the engine out a low pro ****** jack along w/ a good piece of wood (think butcher block thick) bolted down to it comes in handy to bring engine/trans down as a whole.
that's all i can think of right now.
hope this helps
