I just had to change out the front blinker bulb on my 97 sunfire gt, and as far as I know, there were no huge revisions between the 97 and 98 model year, so here's what you'll need to do.
First of all, take out the headlight above the blinker. Your manual should tell you how to do this. Then, simply reach through the hole you've just created to losen the nuts holding the light bulb casing in place, pull it out, and change the bulb. Simple!
how to check fuse for horn in a 1998 Pontiac sunfire
Behind the front right blinker
See stvndberryhill's answer under 1998 Pontiac Sunfire horn relays. This answer applies to all year models of Pontiac Sunfires.
Off the water pump
R134a
check this site------>
22 and 17
Yes
the 98 sunfire haz a 57.2 litre gas tank
It depends on what engine you have. On some you have to remove the housing on the top of the engine which contains the coils etc.
its already got one
One that fits.......