As a 3/3.5E fan, I can tell you this:
You don't need to "learn everything". RPGs are not a wargame like "Advanced Squad Leader". The core rules in 3/3.5E are surprisingly few. Check the rest only if you do something really unusual.
As a player, learn what you can do and be proactive. Ex. Don't wait for your DM to ask "Someone has the XY skill"? Be the first to say "I have the XY skill. Is it useful in this situation?" Or, maybe "I have this spell. Time to use it!" (BTW, keep track of things like your spells' duration). Not only you will lower the DM's burden: you will feel more in control of your character
and, in passing, you will help your DM's creativity (because maybe he hadn't thought that the situation could have been considered from a different angle).
When in doubt (both as the player and the DM) do the most appropriate D20 check against the most appropriate difficulty - and
then (when a pause comes) look for the rule.
3.5E combat is the worst. They tried to force the use of miniatures while shooting down the "mind theatre" style of combat. It required a bit of training but at the end we were able to retain our "mind theatre" battles (with the help of some pencil scrawlings) without ditching the rules.
I speak from experience. My current group came together in 1999 and the core players never changed. I then ran 2E and, after a few sessions, I realised how just everybody was constantly looking at me like a deer in the headlights. After a few months we went to a convention, we played together (with a very pleasant DM who was, actually, in awe when he found out that we were writers and artists for the comic book lines he followed
) and I... dunno... showed how you can be the DM of your character, enjoy the game more, help the DM to be more focused, and, generally speaking, lay the groundwork for a more creative experience.
Maybe a demonstration of what a player can do sometimes is needed. And maybe a lot of choices is not something for everybody. Choices and quality of writing are the twin reasons as why 3/3.5E is my favourite edition ever, but I can understand why some people actually hate it. BECMI (via the "Rules Cyclopedia") will always remain a great alternative.