ECY is great stuff but with it out of stock 99% of the time it gets old.... It's like chasing a Unicorn.
The best sours I have ever made had dregs from 2 bottles of The Bruery Oude Tart in them. Nice solid pop the sour flavor - amazing stuff!!!
those Aleworks direct drive motors are nice BUT at 400 watts that only 1/2 hp. If you use an 2 roller mill you should be fine. For an MM3-2.0 you really need a full 1 hp motor - too bad they don't offer one. I would have snagged it. I have a reducer but haven't gotten off my lazy ass to...
Go for the Platinum Standard! MM3-2.0 with hardened rollers - you'll never look back. Mine is motorized (1 HP motor) with pulleys at the minute. I have my reduction gears - just haven't gotten off my arse to rebuild the mill table yet.
There is absolutely no need to rack off of the yeast bed. Should you decide to to reuse the cake just make sure you carbon dioxide flush the racking vessel and then seal the top with an airlock. A pellicle is not necessary for a sour to develop
Mine is a sour solera and I do not replenish my Sacc yeast at this point so I don't aerate. Now if it is getting too sour I will aerate my wort and pre-ferment in a standard bucket with Sacc yeast and then add to the Solera.