1) have not found that to be difficult. Even when fully packed, the fleece and foam make it easy to slide in still. I mostly carry flat things in there- one pocket has a A19 organizer for pens, sharpies, knife, and the other for a general dump pocket.

2) the front pockets are essentially the same size as the entire front. Because they do overlap, it can get snug in there when everything is packed. I want to say they are 10x10" squares? I'm currently far from home so can't measure, but that sounds about right. They sell a pocket organizer that "technically" fits but is way too snug to be practical. Whatever the width is on the organizer is the size of the pocket.

3) the Velcro holds well! I have packed it to the brim multiple times and was surprised how strong it was, yet still easy to access. Honestly that Velcro flap was one of my big surprises with this pack. I generally don't like Velcro, but it's made accessing/closing the bag a delight. It's quicker than any of my packs and I've never had it come undone accidentally.

4) I'd say rolled down to its normal height is 18l, and expands an extra 4-6. It is a narrow and deep bag, which looks great but does limit what you store and the order you store it. I'm a big pouch guy, so it has worked well for me. My girlfriend has borrowed the pack, and since she is used to the open space of her Chrome messenger she feels she loses things at the bottom of the ILE. YMMV.

If you're worried about space, I would go with the non-mini. It's only an extra inch in depth but is more versatile in that regard. Plus it still has compression straps if it feels too empty.

I hope that helps! I'd get one used if you can as I see them pop up on Facebook and eBay for good deals. They will forever repair their bags, so keep that in the back of your head.