Any mob trap within 16 blocks of the bottom of the map will catch slimes as well, but you have to be careful to not hurt the slimes too much to get them to split the most. Punching and drowning are the safest ways to ensure that they'll split into more slimes. Also, you want a large room so that bigger slimes will spawn which can then have more splits.
The most important thing besides the depth is that it's in a chunk suitable for slimes. Slimes can only spawn in 10% of the chunks, picked randomly depending on the seed. You can calculate which chunks are suitable with this tool by trunkz though: http://www.minecraftforum.net/topic/397835-find-slime-spawning-chunks/
They only spawn a tenth as often as other mobs, but they'll also spawn in any light level, so if you're digging for diamonds at bedrock level, you'll usually find quite a few naturally.
Sadly, no. The Hatch block is an interface to an internal machine state that is incompatible with Managers. A Manager must have an inventory in the vanilla Minecraft sense: a storage space that can both have things added and removed. A Forestry GUI slot (and Buildcraft GUI slots in general) are implemented in such a way that they're merely visual interfaces to a non-inventory (in the Minecraft sense) storage space.
One way you can see the difference is that you cannot use BC wooden pipes to pump items out of an input Multifarm Hatch. If it were merely a block interface to the top-right Multifarm inventory slots, then pumping the input items (seeds, saplings, etc.) out through the input Hatch would be possible. Since you can't do that, a Hatch doesn't connect to a proper inventory. Without a proper inventory, a Manager doesn't have anything it understands as manageable.
Source: tooling around in Creative mode.
In theory, one way to "manage" a Multifarm in a RedPower2 pneumatic tube system would be with a Transposer/Filter/Retriever and exploiting the pneumatic tube "clogged" mechanic to automatically prevent the machine from drawing more items from the connected supply inventories when the farm and connecting tubes are full. However, experiments shows that in practice this doesn't work.
Although Farm Hatches are "clever enough to know which item goes where" according to the Forest Wiki, it also says:
Note: Tubes
RedPower 2 Tubes behave differently from Buildcraft Pipes! This is not a bug.
Through testing, this "different" behaviour is that Farm Hatches are not smart when connected to pneumatic tubes, as everything is dumped into the "soil" slot. With such a large hat put on this "difference" as being "not a bug" in the wiki, I can't help but conclude that this behaviour is intentional. The effect is that Multifarms are mostly incompatible with RedPower2. Consequently, an RP2 system appears to be able to supply humus and other "soils", but not fertilizer or "germlings".
If just maintaining a full soil inventory is enough, then a Retriever makes the most straightforward setup:
This keeps one stack of soil in the Retriever's inventory, which it will automatically eject toward the Farm Hatch as soon as there is any room in the Multifarm's soil slots. The rest of the stack that doesn't fit will "bounce" off the farm, backing up the Retriever and "clogging" it. When clogged, the Retriever refuses to retrieve any more items, preventing the tubes from being full of bouncers. A slow tick (15s in that shot) means that not too many stacks are pulled in the interval between the farm being filled and the clogging backing up the tube system. Any stacks that were pulled in that window bounce off the "full" Retriever. Normally they would continue bouncing back and forth, but adding the extra return tubes lets them go back into the stocking barrels.
As a result, when the farm runs low it refills from the pipe behind the Retriever, the Retriever pulls more to bring its internal inventory back up to a full stack, and any extra stacks pulled (the number is a function of the tick length) bounce around for a bit until they find their way back to the barrels. During normal operation the tubes contain no bouncers for the majority of the time.
Best Answer
The rules for Ender Lilies are actually extremely complicated, as it turns out. See this FTB Wiki page for a comprehensive description of how they work, at least in version 1.0.3c.
Short version:
In other words, this crop forces you to wait a minimum amount of in-game time after planting before you can harvest it. For a crop planted on End Stone in the Overworld on a world that's hitting 20 ticks every second, the absolute best-case scenario outside of using Ender Core (which is very expensive) is that you plant it just before sunrise (50% of the time) and use the Watering Can, then it grows immediately, then sunrise happens and you use the Watering Can again and it grows again, leaving only 5 more growth stages to go through; sleep immediately when possible and use the Watering Can right after sunrise; do this until you can harvest it. All of this will take slightly more than 50 minutes ("slightly more" = it takes a few seconds to go to sleep each time).
If you have the time, read the FTB Wiki page for a more comprehensive explanation about what's going on.