[Andrés]

That's right. All sytem knowledge is the same.
Selecting ancient race is a waste of points.
Most knoledge of far away systems is completely useles, you normally only care about nearby systems, and exploring them isn't difficult.
Identifying homeworlds is not as easy as you describe, espacially in a large quadrant you'll find too many would be homeworlds.
It would only be a nice advantage if you select the option to make contents of all systems visible.
And you can get all advantages of ancient race without exploring the whole quadrant by signing a partership with someone that has it for only 1 turn.

The "As of 2402.5" exploration memory would need some deep hard code changes but it sounds to me like the best solution.
I had suggested it sometime but don't know if I was the first.
You could make it not only remember the planets and racial points, but even alien colonies, and not sure about ships (keeping track of Last know location of every enemy ship would be too much).
I hate not remembering the location of an alien homeworld I had already found but didn't bother to write down.

The more ruins but fewer with useful tech suggestion sounds good. I would avoind the ruin hunting strategy and give it a more random effect. It should be relatively easy to mod.