Forgive me if these are dumb questions, but as a new owner - '75
Sundowner, I'm learning as I go here..

Welcome to the wonderful world of aircraft ownership.

Rule #1: There are NO dumb questions here, because almost everything about
owning an aircraft is counterintuitive. Up is down, black is white, and the
FAA is here to help. ;-)

1. If I install a panel mount intercom myself, I need an A&P to agree
to sign the log. True?

True. Although a previous owner of my plane got around that (sort of) by
using two sheet metal screws to attach a portable intercom to the underside
lip of the panel. (That went out in the trash within a month, in favor of
the panel-mount PS Engineering Intercom/CD player. Which I highly
recommend, BTW.)

2. My nav indicators are a King KI-204 with glideslope and an old
KI-201 or something that is like 30 deg off (2 KX170b's). If I buy a
KI203 on Ebay to match the 204, is it as simple as popping out the old
indicator and pushing in the new one.. will the pins match? Or is this
something I just leave to the local avionics guy?

Are you planning on flying IFR with this aircraft? Do you REALLY want to
slide down an "Ebay Glideslope" in the clag? Some things just cost money,
man; let the avionics shop have a whack at this one.

3. If I replace the wing root seal, do I need an A&P signoff?

If you mean that black rubber thingy at the wing root, no. If you mean some
sort of a speed fairing wing root seal, yes.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"