The guide I pointed to isn't a plugin, just a spreadsheet listing the types of biological things out there, the (old) rewards that scanning them got and the types of body and atmosphere where they can be found. So from that, you will be able to get an idea that if you see an HMC planet that's landable with a sulpher dioxide atmosphere and it has one signal then you will (almost certainly) find Bacterium Cerbrus as usually the first type of signal will be bacterium. Now, if it has two signals, then the second will usually be a Stratum Tectonicas, and that's worth a trip down as they are easy to find and even in the old rewards were worth a lot. The spreadsheet also tells you how far apart signals need to be. I found it very useful as a guide, and pretty soon you'll be looking at a body in the system map and have a pretty good idea what you'll find if you go down.
ED is all RNG, so sometimes you'll get a surprise, but do it a bit and you'll soon be an expert.
You'll also pretty quickly figure out places to land where you are more likely to find what you are looking for. I presume you understand the blue 'heatmap' that shows where a particular bio type might exist, and while for sure there will be times that what you are looking for won't be there, most times in my experience it will be, and since there's often an overlap (an area can be home to multiple bio types) you'll find two or three different things in one area - then you have to back and forth getting three of one then three of the next and so on. When that happens I'll use the SRV and drive between them. For bacteria I usually do that from the ship, they are easier to spot from above.But you're right, for all the weakness in the exobiology gameplay it does give a reason to land and actually do something other than take a screenshot and variety is the spice of life!
And what you find doesn't really depend on the distance you go, just the type of body and its atmosphere type. Of course, further out means stuff is less likely to have been discovered before so you'll get more first discoveries which means more credits and your name on the system map for bodies you've scanned and mapped (once you sell the data).
