stems, snap, probably ok.
a little jiggle and the should bounce around fairly freely, yes.
you'll feel they are quite dry on outside when you put them in (when stems snap). After 24 hours check on them. if they get too soft or moist on outisde again, you leave the jar unsealed for a while. Seal it back up and rinse and repeat again tomorrow. The last few percent of moisture should be while curing. (down to 8-10% when done or something like that... there is still some moisture content when done, if done right, or it will just crumble to dust)
a 2-way humidity pack gives great room for error. It can absorb and dispense water vapor. it will maintain a 55-62% RH, depending on which pack/brand you buy. Anything in this range is great... personal preference for how much moisture remains. It has limits... so if you put it in too wet, it can only absorb/release so much... you still likely have to leave a jar open occasionally if a bit too wet to start even while using 2way humidity packs.
You need to burp during this process... replensish O2 so you don't grow anaerobic bacteria, which is what stinks like pickles or other odd and foul smells. Once curing is done, don't need to burp as often, but should do it occasionally. Some of the finer points i'm still working out... at what point can i set burping to 1/week? etc... but the outline is solid, i think,
if you ever scale up, fine a way to automate the burping proces... a few jars is one thing.. .24-48+ is just fucking ridiculous. check out the guy with the auto burping system using 5-gallon buckets with gamma lids on youtube... easy to extrapolate from there.