Pretty sure defrosted EBM needs to be used within 24 hours - it might be when it's defrosted in warm water that it's 5 hours. I would take it from when it is fully, or mostly defrosted.

How often is bub feeding? You might be able to defrost in warm water (or at least speed the process up) and split it into 2 bottles, put one straight back in the fridge. I would think it would be fine for a few hours until the next feed, especially if it's not actually getting warm (I found quite often when i defrosted EBM there was a point where it was liquid, but not warm IYKWIM).

The crystals are probably watery bits of EBM or maybe milk fat that is still frozen? I think if it's been in the packet with the milk, it's fine to tip in the bottle.

HTH

ETA - ABA guidleines are as follows: (link HERE)

Freshly expressed into a closed container
Room temp - 6–8 hrs (26ºC or lower). If refrigeration is available store milk there
Fridge - 3–5 days (4ºC or lower) Store in back of refrigerator where it is coldest
Freezer 2 weeks in freezer compartment inside refrigerator.
3 months in freezer section of refrigerator with separate door. 6–12 months in deep freeze (-18ºC or lower).
Previously frozen— thawed in refrigerator but not warmed
Room temp 4 hours or less (ie the next feeding)
Fridge Store in refrigerator 24 hours
Freezer Do not refreeze
Thawed outside refrigerator in warm water
Room temp For completion of feeding
Fridge Hold for 4 hours or until next feeding
Freezer Do not refreeze
Infant has begun feeding
Room temp Only for completion of feeding, then discard
Fridge Discard
Freezer Discard