A Nat 20 is not automatically a critical success. It increases the success level by 1.
So; attack 1 = Nat 20. Add in all modifiers. If it's a hit, it is a critical success. Subsequent attacks = Nat 20. Follow the same procedure. But it's more likely to be a miss due to iterative attack penalties. If it's a miss, a Nat 20 will make it a hit.
Same for saving throws. If you roll a Nat 20 and for some reason the total derived number still fails, it turns into a success, not a critical success.
Weapons which require loading times cannot be stored loaded unless it makes sense to do so, and there may be unanticipated consequences of doing so. If you have quick draw, I will say you can use 1 action to draw the weapon and fire and another action to load, so 2 actions to quick draw a light crossbow instead of the normal 3 to draw, load, and fire
You can use actions in any order you wish during your turn, but you have to complete one action or activity before beginning another; for example, you can’t use a single action in the middle of performing a 2-action activity. What actions you can use often depend on your class features, skills, feats, and items, but there are default actions anyone can use, described in Basic Actions below. Some effects might prevent you from acting. If you can’t act, you can’t use any actions, including reactions and free actions.
If you begin a 2-action or 3-action activity on your turn, you must be able to complete it on your turn. You can’t, for example, begin to High Jump using your final action on one turn and then complete it as your first action on your next turn.
Once you have spent all 3 of your actions, your turn ends (as described in Step 3) and the next creature’s turn begins. You can, however, use only some of your actions and end your turn early. As soon as your turn ends, you lose all your remaining actions, but not your reaction or your ability to use free actions.
A creature called by a conjuration spell or effect gains the summoned trait. A summoned creature can’t summon other creatures, create things of value, or cast spells that require a cost. It has the minion trait. If it tries to cast a spell of equal or higher level than the spell that summoned it, it overpowers the summoning magic, causing the summoned creature’s spell to fail and the summon spell to end. Otherwise, the summoned creature uses the standard abilities for a creature of its kind. It generally attacks your enemies to the best of its abilities. If you can communicate with it, you can attempt to command it, but the GM determines the degree to which it follows your commands.
Immediately when you finish Casting the Spell, the summoned creature uses its 2 actions for that turn. Summoned creatures can be banished by various spells and effects. They are automatically banished if reduced to 0 Hit Points or if the spell that called them ends.