Bought my first plane:-D

So I put a deposit down on N4261J, a Piper Cherokee 140 (that I
mentioned in an earlier post).

The previous owner had nicknamed her 'Julie' (for obvious reasons)...
My fiancee fell in love with the name so I think it's stuck

I don't think I have ever been quite so excited, I feel like a kid
before christmas

She's in getting her out-of-hibernation annual done. The previous
owner (A former United A&P) didn't tell me (why I can't imagine), but
during her prepurchase inspection, the mechanic noted that the engine
was flawless because the owner had properly prepared it for indefinite
storage.
An oil change and some new hoses and she fired right up and purred like
a kitten. She's also going to need the fuel tanks resealed and the fuel
and brake lines redone, all and all around 7k worth of work...
(Purchase Price + Annual = 21K)

Now... I have (a long list) of questions as a new aircraft owner

1- Refinishing. Julie's paint is faded, but otherwise in good shape.
Are there any combinations of refinishers/waxers that could get her
reliably back to a shine? A quick search online suggested Meguiars
products- would a simple wax do the trick? or are there any other
refinishing products I should use first?

2- Interior Trim,
The Rubber doorseal is shot, is that an easy replacement? Also, the
pilot's seat and armrest are both cracked and leaking foam, and quick
suggestions to fix them?

Upgrades - There are a few upgrade luxuries I'm looking in too, I'd
love some feedback-

1- Autotrim... Ok, Pure luxury, I know... but the plane I rent has it,
and I'm absolutely spoiled (and hell, its my plane right?) The S-tec
manual trim system is STC's for the Cherokee 140, and it seems to
retail for around ~2k online... Any thoughts?

2- Aspen Avionics AT-300... I don't consider this so much a luxury as a
safety issue. Julie is west-coast based... and unfortunately we do
have big rocks here that can happen to get in the way of little planes
(even more so because I plan on taking her across the rockies at least
a few times to go visit my family back east). Now- do I need an STC to
install the AT-300? (it is a Certified replacement for the VSI) I've
noticed that there are a couple instrumentation STC's for the Piper in
the FAA database, but none for the AT-300 on any aircraft - is there a
special rule for primary instruments? (Also, The current 'shotgun'
layout of the panel isn't quite what I'd like, is there anything
special I'd have to deal with just moving a few of the guages around to
a layout that suits me better?)

3- King KL135 A - She has a single KL170 currently... I'm used to
dealing with aircraft with dual Comms, so that will take some getting
use to. But the AT-300 requires and external GPS, so I tempted to just
trade in the existing KL170 + CDI for a King KL135 A GPS/Comm unit.
I've heard that when it comes to modern Comms, GPS based are the only
way to go (because of the ability to select from a list of local
frequencies, based on the internal Jeppeson Database). The local
avionics shop suggested that if I do get a GPS/Comm, I go ahead and get
one with future IFR capability (something I plan on doing down the
road). They also mentioned that the KL135 can interface directly with
an intercomm without an audio panel for the time being, which helps to
save some expense (Julie's previous owner didn't have an audio panel or
intercom, she just used a handheld mic and the aircraft speaker). My
eventual goal would probably be to drop in King KX125 + Audio Panel
when I went to make her a full IFR aircraft, but that's a future
project.

4- Power
Going along with the whole Ability-to-cross-the-rockies thing, I am
seriously considering going ahead and-
A- 160hp stc
B- Powerflow Exhaust
C- AM&R tip mod + 62" prop repitch
There's absolutely no reason why I need it now, but I know i'll need it
eventually, so part of me thinks I should build it into the purchase
price.

5- Aerodynamics
Do any piper owners here have experience with the AM&R wingtips and
VG's? They seem to have a decent reputation online and they're very
inexpensive (1000 total).

Note - none of this is for 'investment' purpose (I don't care if I
wouldn't make it back when I sell her, because I don't plan on doing
that for quite a while) This is about making my plane what I want
her to be

Thanks in advance for any insight you guys may have

-Scott