alright, first of all, yes. an oil leak between the bellhousing and the block will be a leaking rear main seal.
this is actually a pretty easy job if you have everything you need.
are you getting an aftermarket clutch, or an oem?
if you go aftermarket, i recommend getting an adjustable
clutch cable and a solid one piece quadrant. make sure the clutch kit comes with a
pilot bearing and throwout bearing.
are you buying a new flywheel or resurfacing your old one?
for tools, you'll need a 3/8 ratchet, metric & sae sockets (3/8 drive), a prybar about 2 feet long, a VERY LONG 3/8 extension, about 4 feet long...you can just take 3 or 4 regular sized extensions and stack them. whatever works for you. also, a 3/8 torque wrench; 10-100 ftlbs range is best.
other than that, some loctite, a can of brake clean, some caliper grease and 7mm drift punch for your rear main seal. also, you'll need some black rtv silicone for your shifter since it needs to be removed. and, keep a quart of atf handy, you'll lose some
trans fluid when you remove your driveshaft. if you should happen to have an extra yoke lying around that fits your transmission, you can put that into the tailshaft to minimize fluid loss. if not, a rag and some paper towels should work until you get the transmission on level ground. just be careful not to mess up the rubber seal in the tailshaft.
that should be your complete list of stuff necessary to get the job done.
if you dont have a
trans jack, get a friend or two to help you drop the transmission. you'll want a friend anyway to hold the prybar for you while you disconnect the clutch cable from the clutch fork.
a basic rundown of steps;
disconnect the negative battery cable
remove your shifter, 4 bolts holding it on.
disconnect rear o2 sensors.
remove your exhaust midpipe
disconnect and remove your starter.
remove your transmissions dust shield (1) 3/8" bolt holding it on
remove the (4) 12mm bolts (you need a 12-point socket or box end wrench for this) on your driveshaft u-joint. (use some PB blaster, those bolts are very tight)
remove driveshaft by sliding it out of the tailshaft of the transmission.
remove the transmission crossmember, (2) 13mm bolts.
support the transmission, then remove the (4) 15mm bolts holding the transmission to the bellhousing. slide the transmission out.
remove the bellhousing bolts, (13mm), once the
trans is out you can pull the engine down by hand a little bit, giving you some much-needed room to get the top 2 bellhousing bolts.
remove the bolts from the pressure plate.
remove the clutch assembly.
remove the (6) 19mm bolts holding on the flywheel.
use either a pilot bearing puller or a slide hammer to remove your pilot bearing.
use a pick to carefully remove the rear main seal.
after all that, installation is the reverse of removal.
use brake cleaner to spray down your new/resurfaced flywheel, and also spray down the clutch disc and the friction side of the pressure plate. doing this, along with even torquing of the pressure plate to the flywheel, will prevent clutch shudder/chatter.
use the drift pin and a small hammer to tap the rear main seal into place, going in a up/down/left/right pattern. listen closely while tapping it in, the tapping will make a different (clink) sound when the seal is fully seated.
flywheel bolts are torqued to 80 ft.lbs.
pressure plate bolts are torqued to 24 ft.lbs.
bellhousing bolts are torqued to 38 ft.lbs.
changing the clutch on my 1999 Mustang 3.8 
