Okay, so both sentence 1 and sentence 2 are perfectly good sentences, but neither of them quite mean “We’d like to hold meeting A before/after meeting B.”
"in conjunction with" means 'together with'.
In this context that could be one immediately after the other, but it could also be at the same time. (If it is one after the other, it also doesn't say which one first.)
"taking advantage of" means 'to put to good use'.
If meeting A is taking advantage of meeting B, I guess A would probably be after B so you could put what got decided in B to use in A. However, it could be straight after, or it could be days after.
All the sentence is saying is that you'll be using something about the other meeting (which could even be you're taking advantage of people being away at that other meeting, to have a meeting without them)