you're better off asking about FPV in the actual FPV forum, much more specific info there than in here... anyway
there is a completely better choice of setup. The AVL58 is widely regarded around here as the worst of the 3 major options (ImmersionRC, Boscam, or AVL58) as the AVL58 itself is physically heavier, draws more power but outputs less, all of which yields to less flight time for less FPV performance. Also the hub adds weight and the cables aren't long enough for clean, internal install. You were planning on doing an internal iOSD Mini install, yes? you really should it's too easy not to.
You're better off going with either an ImmersionRC 600mW, or Boscam transmitter (TS352 or TS353) ... both of which have plug-and-play cables that perform the same function as the DJI FPV hub (which only works with AVL58) but much simpler and lighter.
I'd suggest you take a look at this stickythread in the FPV forum, it's got links to all the components you need, the plug and play cables I mentioned (different ones for IRC vs Boscam), and maybe even a few items you haven't thought of (like the display mount):
viewtopic.php?f=34&t=26413
as for your question about monitor: If you go with the ImmersionRC 600mW transmitter, you'll want the 8 channel Black Pearl: many folks on this site have posted about strange issues with the 32 channel.
Alternately, the RX-LCD5802 display is cheaper, and still a 32 channel so it works with either transmitter family and again many people around here have posted saying it works perfectly fine with the IRC transmitters. I know it works great with Boscam.
definitely consider some good antennas, as really the quality of the antennas you use can affect your FPV performance more than just the transmitter power. shitty cheap antennas on a 600mW will perform way worse than premium antennas on a 400mW for example.
hope this helps!