Fuel Sending Unit ?s

Still have my wacky gauge problem - now it is going all the way up then all the way down, then back again.

Anyway, I was looking at the sending unit via the trunk and had a couple of questions:
1) Are the fuel pump and sending unit all in one? I see an electrical connesction as well as fuel lines. Is this big plastic thing both?
2) Are these lines pressurized?
3) Without any other mech problems seemingly related to this (other than the fuel gauge issue), should I even bother with it at this point? Are the other stalling, etc. problems I read about inevitable - meaning if I don't replace it now, I will have to later? (1997 ~100k miles).

Love this car, hope to keep it for few more years, 50+k miles.

Thanks to all.

Brian

Pump and sendy are one unit - dealer part 350
get the tool for the retainer ring if you can and CLEAN OFF THE TOP OF THE TANK FIRST.
lines are presurized so I pulled elec connection and then started car - a couple more turn overs after it stalled to depresurize - use shop cloths when disconnecting lines - 30 min job if all goes well and your trunk is empty.

Thanks TJM