Everything you need to know.

Flexcubes are UV stabilised and when empty, can be safely stored outside. Full Flexcubes should of course be placed in a protected and preferably temperature-controlled cellar environment. Flexcubes in pearl colour are UV stable, but do pass visible light. If storing wine outside or near a window, use the opaque grey Flexcube or fit a cover. When storing empty Flexcubes, care must be taken to ensure they are clean and dry to promote a hygienic internal environment. There is no need for the use of SO2 in storing the Flexcube if it is stored clean & dry.
The ribs on the main seal are for orientation, as the main seal has a 'right way up' and a 'wrong way up'. They indicate the side that should face downwards (toward the wine) - always ensure the rib on the main seal are facing downwards as fitting the seal incorrectly will reduce its sealing capability.
Flexcubes are available in three permeabilities: Low (LP) 6mg/L/yr; Medium (MP) 9mg/L/yr; and High (HP) 12mg/L/yr.
Low permeability is better suited for whites and those red varieties with low tannic and phenolic content (often Grenache responds better to LP). Medium permeability is the most versatile option, works very well with most Cabernets, Shiraz, Pinotage, Pinot Noir, Carmenere and Merlot. High permeability ideal for varieties with high tannic and phenolic content where a softer finish or earlier release is beneficial (Petite Syrah will often respond better in HP)
Because there is plenty of O2 available during ferment, the permeability of the Flexcube is of little influence during fermentation and immediately afterwards (say 1-2 months). So you can ferment in any permeability. For maturation, however, LP is highly recommended (essential). Chardonnay and other white 'broaden' and 'fatten' quite quickly in MP Flexcubes
Ullage - Check fill height every 4-8 weeks as thermal expansion/contraction will always occur with wine temperature changes. SO2 - Check and adjust SO2 levels as you would in a traditional barrel (a typical cellar will do this every 4-8 weeks). Reductivity - If there are signs of reductivity in your wine, rack and return as you would in a traditional barrel.
Within 2 weeks of filling, the Flexcube must be topped, as the polymer walls will initially stretch. Unless the wine is undergoing primary or malolactic fermentation (when it must be vented), maintain the Flexcube completely full, the same as a traditional barrel.
No. Due to their weight, and subsequent change of force on the main seal, liquid-filled expansion chambers are not to be used with Flexcubes (and are unnecessary anyway). The use of such chambers will void the warranty.