So after a few years off I'm going to try and dust off my ships and re-learn how to play. I have a few questions...

1) Suggestions on ships to consider adding to my Rebel collection. I have X-Wings, Y-Wings, B-Wings and an A-Wing. Looking to fly with the Rebels.

2) My son also wants to learn how to play, and he's interested in Imperial and Scum. We have a few TIE fighters (starter set) and a Star Viper. What should I consider adding for him?

Also any build suggestions for beginners would be helpful. Thanks in advance!

So, I'd say for sure get Heroes of the Resistance, Imperial Veterans, and the First Order TIE Fighter. That presents you with many, very nice options, and frankly, a few lists where you'd only need a couple other purchases to own all the cards (if you wanted to go to a tourney).

For Imperials:

Countess Ryad

TIE/X7

PTL (you might have it with an A-Wing? If not, proxy or purchase with Rebel Aces)

Twin Ion Engine Mk. II (proxy or purchase with TIE Punisher)

Tomax Bren

Crack Shot

Unguided Rockets (proxy or purchase with TIE Aggressor)

Light Weight Frame (proxy or purchase with TIE Aggressor)

Extra Munitions (proxy or purchase with TIE Punisher)

Your choice of bomb, but probably a maneuver bomb

Omega Leader

Juke

Comm Relay

Stealth Device (optional, available in several ships)

For Rebels, as a rebel player, I can see MANY options. Here's one:

Poe Dameron (PS9)

Veteran Instincts (proxy or purchase with many ships)

Advanced Optics (proxy or purchase with TIE Silencer or Resistance Bomber)

Flight Assist Astromech or BB-8 (proxy or purchase with Sheathipede-Class Shuttle or Force Awakens Core Set, respectively)

Autothrusters

Black One

Rey

Veteran Instincts (see above)

Finn

Kanan Jarrus (proxy or purchase with the Ghost)

Millenium Falcon (TFA title)

Smuggling Compartment

Countermeasures (proxy or purchase with YT-2400)

Scavenger Crane (proxy or purchase with Quadjumper)

These are both well rounded, fairly easy to fly lists. They take skill, but aren't confusing in nature. The Imperial One is definitely the cheapest to theoretically take to a tournament, but if you are okay with proxying, you can fly them both simply with my above suggestions. Keep in mind, you already have enough of a selection to build many lists!

Welcome back to the game!