That's not errata. Just someone's home-brewing is all.
I second this. I suggested some ideas and some of my own house rules then I realized how far that thread had gotten from actual errata.
Official MgT 2e Errata does not exist to my knowledge but there is this thread on the MgT forum:
http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=120907&p=925059&hilit=2e+errata#p925059
It covers quite a bit of the new 2e core rules with answers from the author himself.
I personally really like the MgT 2e version. It feels old school in it's simplicity, yet it addresses the new generation with some tweaks to the starkness of Classic.
I should say I was not a fan of MegaT because I found it very rules-intensive for a lot of what should be (IMO) simple things, mainly task resolution and combat damage. And of course - the massive errata. Designing a ship and then finding out it didn't work was frustrating, to say the least.
I haven't played any real games with Cepheus Engine but I have the rules and vehicle supplement and they are very good. I've made some characters and some vehicles and so forth and I feel like you can't go wrong with this route.
MgT 2e greatly simplifies vehicle design and I think it's a better system and much faster to design with (versus MgT 1e / Cepheus; I would never design a vehicle in MegaT). It also seems more in the spirit of T5, where small spacecraft and vehicles are designed more with size and useable traits rather than exactly detailing components, requirements and capabilities and making sure it all fits/works. It works from the get-go, it's just the more you add, the more expensive/bigger the craft gets. There are a few trade-offs you might have to do so that keeps it interesting.
Personally I would go with Mongoose 2nd Edition. It's alive and there are adventures/supplements being published right now. I suppose there are errata concerns with both Mongoose versions but quite frankly they haven't hindered me personally. CE is alive and well but is fan supported/OGL.
Last, Mongoose have been doing a lot of interesting and fun work with the pre-Rebellion 1105 era Third Imperium; that has breathed a lot of new life into the setting. Since you're starting your campaign pre-Rebellion you can just roll right into it when you're ready.
I can't think of any rules in any version that are rebellion-specific, except maybe adjusting some UWPs.