and why blocks with more coins have bigger "mintprobability"?
Info in the minting tab can often be inaccurate. However you can enable coin control and look at your Send tab, select inputs, select list mode, sort by confirmations. This allows you to see what blocks are the oldest and ready to stake (they have coindays) . To take advantage of compounding and earn your stakes the quickest, combine all the blocks into one. When they stake they will split into 2 blocks, quickly recombine them and start the next stake period. Think of amount 808 in your block as your mining power, it will have greater mintprobibility and likely stake quicker. Proof of stake has a mining difficulty system so the amount of 808 needed to stake quickly changes. From recent posts i would say its a fair bet 1 million 808 will stake on the 8-9th day(almost immediately when its eligible).