I fish Busch 2-3 days a week and MO_LMB has given some good advice. I'm currently spending some time charting the lakes and uploading all of the info to Navionics, so if you have access to the app, keep an eye out for updates. So far I am filling in Lake 6 in pretty well, but I'll be working on 35 tomorrow morning.
35 is also my favorite and is always good for numbers if nothing else. Biggest I've caught there this year so far was 3lbs 13oz. I've had plenty of 20+ fish days there. Clear water, but lots of vegetation. It ranges from about 2 to 24 feet in depth. There is a lot of timber but you won't find it without getting snagged on it or having a depth finder. There is a cove that has a deep channel (about 12 feet) running through it. No one seems to fish the channel because it's hard to find and tough to pick out the grass edges. When you figure it out though, there will be fish there.
Never fished 33. Too many people usually for me, but once the temp drops, I'll hit it up some weekday. 38 is a mini 35 in regards to vegetation. Again, lots of trees and brush. 30 has potential. I've caught several from the bank on top water. Nothing real big but I haven't spent much time there either. 34 is lily pad heaven but I've only fished it twice and the bass weren't cooperating. Did catch a couple in the 1-2 pound range on a whopper plopper near stumps though.
The boat keys are not all universal although they sometimes do work on multiple lakes. It is just as easy to go back to the Outpost tackle shop and swap keys. Plus, they really appreciate it because it helps them track the boats. Some lakes have limited boats so if you are tieing up the lake key, but not the boat, it still makes the boat unavailable.
Like I said, I am there all of the time, so if you want a tour, let me know. I have my company work van most of the time, so I'm easy to find.