I have an early 01V and the metering stinks. Like most digital mixers of it's time. Maybe even still, for all I know.
If direct outs is not an option (i.e., not enough inputs to the computer, or you want to mix the synths while tracking), what you want to do is hit the A/D converters reasonably hot (without clipping), and adjust the output gain to keep the recorder happy. Works about the same in live situations.
Anyhow, here's what works for me. It's close to your option 1).
1) Pick a reference level for the average or typical signal. I use about -18 dB, -12 if there isn't much dynamics to the stuff coming in. This refernce level would comparable to "0" on an analog desk. You can't bother getting too precise on this part, 'cause the metering stinks.
2) set the input gains so that the inputs are running about that level. The peaks may be getting close to 0 dBFS, but not going over. If it goes over, reduce the input trim.
4) mix channel faders to suit. Most will be around 0, give or take a bit.
3) when a lot of inputs are summed to the stereo bus, the output may go over 0 with the main fader all the way up. That's OK, just reduce the main fader until the output isn't clipping. Again, you want to run it reasonably high, without going over. With a lot of hot channels mixed to stereo, the master fader may be 12 - 16 dB down. If you are doing a lot of EQ and/or compression, it may need to be even lower. That's still OK - it's pretty hard to clip the internal mix bus.
Note that the EQ and compression pages have gain trims to help you manage internal bus levels.
So long as you get good levels at the A/D, where you fade things matters,but not that much - there's usually enough computing range in the digital end of things to make it come out oK.
Wayne