1st: AE cannot fully simulate a supplier pipe. It is impossible to keep a certain amount of items stacked in a specific inventory. Even level emitter and subsystems are only cruches that fail as soon as the crafting of an item takes more than some ticks.
2nd: LP and AE are best connected by a MKII with itemsink and provider module and a request pipe to an ME interface. The request pipe makes LP fully accessible for AE including any crafting; the provider ans itemsink module make AE acessible for LP.
3rd: LP cannot use the crafting in AE. This is due to the different approach from both systems. LP does a simulation first to calculate all the needed materials, AE just starts crafting.
4th: AE itself can't handle liquids. Maybe it's possible to send the LP liquid container item thingies through an AE system but I didn't try, yet.
5th: AE can transfer LP power so you can group several LP subsystems around an AE central bus and still need only one LP power provider.
6th: never connect two systems at more than one point. Several subsystems are valid, but each subsystem should only connect once to the main system. Otherwise there will be unforseeable efects.
I'd suggest you combine both systems. LP is a logistics system and AE is a storage system. Both can craft, but do it different with the corresponding (dis-)advantages. I haven't found the best combination, yet, but I'm still searching. ATM I have AE for storage, internal crafting(crafting core) and manual access (ME crafting interface) and LP for the rest. The drawbacks are I cannot access autocrafting from a remote orderer and things need time to zip through the buildcraft pipes from A to B.