I don't think there are, or if there are, they are very few. There are mentions in Zahn's novels - cloning technology actually plays a pretty large role, one of the new characters is a founding member of the Rebel Alliance, etc, but it is all based on pretty much just what we were told in the OT (and is also limited based on what Lucas nixed from story proposals). The date of the end of the Clone Wars is 35 years before the battle of Yavin, though. (This came from LFL between the first and second books in Zahn's trilogy.) Children of the Jedi has a different date, if I recall. There are some other bits sprinkled throughout the rest of the pre-PT EU, but nothing super cohesive. Or rather, it's cohesive in the same straightforward way as the clues in the OT. The Republic fought a war involving clones, Palpatine came to power, Anakin Skywalker was seduced by the dark side, the Jedi were extinguished. The mention in the ESB novel of Boba Fett's armor being originally worn by warriors defeated by the Jedi in the Clone Wars fed the idea that the Republic fought Mandalorian Supercommando clones in the Wars. Important to note, there is no inkling of a grandiose metaphysical Sith plot to destabilize the Force. Vader is the Dark Lord of the Sith, Palpatine doesn't officially become one until TPM. And the balance/Chosen One thing comes completely out of left field in 1999. And there are dark siders active throughout the timeline, almost none of which are Sith. These dark siders may also have had something to do with the Clone Wars, as they pop up in that historical era in books like HTTE and I, Jedi.
Also, regarding Anakin's age: my mental image of him is heavily based on what I get from watching ANH, in which he is (/was originally) a separate character from Vader. Vader is clearly intended to be a younger character than Ben, a "boy." But Annikin (different spelling) is, I think, meant to be intermediate between this and Ben's age.
There was a big discussion of this on TFN one time, I'll have to try to dig it up. Basically it seems that Lucas had created two characters in ANH - Vader, who's definitely young, and Luke's father, for whom no age is given. But his attributes seem to be somewhat similar to Obi-Wan's, and in the script Blue/Red Leader says he met Luke's father, who was a great pilot, when he (Blue Leader) was just a boy - and that character is probably 45ish in the film. (This is in the scene that was partially restored in the SEs - here's bts footage of it being filmed, with part of the original bit audible.) If he's 45ish, and met Annikin when he was, let's say, 5-10 years old... Annikin was probably Luke's age (20ish, barring podrace-type shenanigans - I think Annikin and his journey were meant to mirror Luke and his in a lot of ways in the OT) 35-40 years before. So Annikin would have been 55-60 or so at the time of ANH (if he were alive). And he'd have been 30-35 when Luke was born. In ROTJ's script, Anakin is described as "elderly," and Shaw definitely looks close in age to Ben.
(There is some variability with those ages. Interesting that Obi-Wan did start out 30-35ish in TPM, and was de-aged when Qui-Gon's role was expanded - if I recall.)
I think that Anakin and Vader's ages differed from the beginning, and Lucas chose the older of the two possibilities when he first combined the characters. Later, he changed his mind and gave Anakin the younger age when he went to make the prequels.
EDIT: Just remembered, there's something in Marvel about Princess Leia having something to do with the clones or the Republic? I think this is in the issues with the Mandalorians? I've only seen oblique mentions, I don't know the details of this.