Can you cast 2 spells in a turn?

Yes, you can cast more than one spell per turn/round. The only specific restriction is that if you cast a spell as a bonus action, you can’t cast a non-cantrip spell during your turn. You can: Cast a spell as an action, use Action Surge, cast another spell as your second action.

When can you use bonus actions?

You can take a Bonus Action only when a Special ability, spell, or other feature of the game states that you can do something as a Bonus Action. You otherwise don’t have a Bonus Action to take.

Can you do your bonus action first?

Or does a Bonus Action have to follow an Action? Yes, you can take a Bonus Action first, unless it’s an ability that specifically states that it has to follow after something else, such as Crossbow Expert’s bonus attack. This is the most correct answer. Bonus Actions can be used any time during your turn.

Can you take a bonus action in the middle of an action?

No general rule allows you to insert a bonus action between attacks in a single action. You can interrupt a multiple-attack action with a bonus action/reaction only if the trigger of the bonus action/reaction is an attack, rather than the action.

Can I use Eldritch Blast as a bonus action?

Do note that eldritch blast has a casting time of 1 action. You will need some way to modify that casting time (such as the quicken spell metamagic) to cast it as a bonus action. As a further note, also remember that you cannot take a bonus action unless some feature or ability allows you to.

Can you divine smite twice per turn?

TL;DR: other than “1 spell slot per attack” and “max 5d8 damage or 6d8 versus undead/fiends per use of divine smite” there are no limits. 1 divine smite per attack, but no limit per turn.

Can a paladin smite twice a turn?

Yeah, paladins can smite as many times as they hit if they have the spell slots.