1. can i treat the sound engine on the moxf8 as a vst so that i can go in and manually edit notes in and out to tighten up my songs? If so how can i do this?

Yes, the "MOXF6/MOXF8 Editor Standalone/VST" allows the MOXF to be treated in a similar fashion to how soft synths are treated on the computer, even though the Tone Engine of the MOXF is an EXTERNAL device. It is a routing scenario of MIDI and returning audio. How you do this with FL Studio is really a question for them. I can show you how to setup and use the MOXF VST inside Cubase.

2. is it possible to have the MOXF8 connected and synced to my daw but use another controller (Roland JD-XI) to play the sounds? i've tried in FL 12 and cubase. it registers that i'm hitting keys on the jdxi but no sound plays, however, the jdxi does work for controlling my other vst's.

Yes, you can setup your DAW to use multiple controllers, this is not a difficult thing. Again, I cannot help you with FL Studio but can show you how in Cubase.

In Cubase you can select multiple devices to be MIDI INPUT devices. MIDI PORT SETUP you get to define which connected MIDI Devices are going to be sources for incoming MIDI data. The column marked "In ALL MIDI Inputs" - lets you define which of your devices are going to be INPUT devices. So you would mark the MOXF-1 (port 1) and the Roland Jdxi's MIDI Port as INPUT Devices.

Then when you create a MIDI Track you set the INPUT to "ALL MIDI INPUTS" - this will allow the marked devices to act as MIDI Input devices to the Track.
Each DAW has a different way of doing this. Again, I do not know FL Studio, but I'm sure it has an equivalent method of selecting multiple MIDI Input devices.